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Config(3perl)           Perl Programmers Reference Guide          Config(3perl)

NAME
       Config - access Perl configuration information

SYNOPSIS
           use Config;
           if ($Config{usethreads}) {
               print "has thread support\n"
           }

           use Config qw(myconfig config_sh config_vars config_re);

           print myconfig();

           print config_sh();

           print config_re();

           config_vars(qw(osname archname));

DESCRIPTION
       The Config module contains all the information that was available to the
       Configure program at Perl build time (over 900 values).

       Shell variables from the config.sh file (written by Configure) are
       stored in the readonly-variable %Config, indexed by their names.

       Values stored in config.sh as 'undef' are returned as undefined values.
       The perl "exists" function can be used to check if a named variable
       exists.

       For a description of the variables, please have a look at the Glossary
       file, as written in the Porting folder, or use the url:
       https://github.com/Perl/perl5/blob/blead/Porting/Glossary

       myconfig()
           Returns  a  textual  summary of the major perl configuration values.
           See also "-V" in "Command Switches" in perlrun.

       config_sh()
           Returns the entire perl configuration information in the form of the
           original config.sh shell variable assignment script.

       config_re($regex)
           Like config_sh() but returns, as a list,  only  the  config  entries
           who's names match the $regex.

       config_vars(@names)
           Prints  to  STDOUT  the  values of the named configuration variable.
           Each is printed on a separate line in the form:

             name='value';

           Names which are unknown are output as "name='UNKNOWN';".   See  also
           "-V:name" in "Command Switches" in perlrun.

       bincompat_options()
           Returns  a  list of C pre-processor options used when compiling this
           perl binary, which affect its binary compatibility with  extensions.
           bincompat_options()  and  non_bincompat_options() are shown together
           in the output of "perl -V" as Compile-time options.

       non_bincompat_options()
           Returns a list of C pre-processor options used when  compiling  this
           perl   binary,   which  do  not  affect  binary  compatibility  with
           extensions.

       compile_date()
           Returns the compile date (as a string), equivalent to what is  shown
           by "perl -V"

       local_patches()
           Returns  a  list of the names of locally applied patches, equivalent
           to what is shown by "perl -V".

       header_files()
           Returns  a  list  of  the  header  files  that  should  be  used  as
           dependencies for XS code, for this version of Perl on this platform.

EXAMPLE
       Here's a more sophisticated example of using %Config:

           use Config;
           use strict;

           my %sig_num;
           my @sig_name;
           unless($Config{sig_name} && $Config{sig_num}) {
               die "No sigs?";
           } else {
               my @names = split ' ', $Config{sig_name};
               @sig_num{@names} = split ' ', $Config{sig_num};
               foreach (@names) {
                   $sig_name[$sig_num{$_}] ||= $_;
               }
           }

           print "signal #17 = $sig_name[17]\n";
           if ($sig_num{ALRM}) {
               print "SIGALRM is $sig_num{ALRM}\n";
           }

WARNING
       Because this information is not stored within the perl executable itself
       it  is  possible  (but unlikely) that the information does not relate to
       the actual perl binary which is being used to access it.

       The Config  module  is  installed  into  the  architecture  and  version
       specific  library  directory ($Config{installarchlib}) and it checks the
       perl version number when loaded.

       The values stored in config.sh may be either  single-quoted  or  double-
       quoted.  Double-quoted  strings are handy for those cases where you need
       to include escape sequences in the strings. To  avoid  runtime  variable
       interpolation, any "$" and "@" characters are replaced by "\$" and "\@",
       respectively.  This  isn't  foolproof, of course, so don't embed "\$" or
       "\@" in double-quoted strings unless you're willing  to  deal  with  the
       consequences.  (The  slashes will end up escaped and the "$" or "@" will
       trigger variable interpolation)

GLOSSARY
       Most "Config" variables are determined  by  the  "Configure"  script  on
       platforms  supported  by  it  (which  is  most  UNIX  platforms).   Some
       platforms have custom-made "Config" variables, and  may  thus  not  have
       some  of the variables described below, or may have extraneous variables
       specific to that particular port.  See the port  specific  documentation
       in such cases.

   P
       "PERL_API_REVISION"
           From patchlevel.h:

           This  number  describes  the  earliest compatible "PERL_REVISION" of
           Perl ("compatibility" here being defined as sufficient  binary/"API"
           compatibility  to  run  "XS"  code  built  with  the older version).
           Normally this does not change across maintenance  releases.   Please
           read the comment in patchlevel.h.

       "PERL_API_SUBVERSION"
           From patchlevel.h:

           This  number  describes the earliest compatible "PERL_SUBVERSION" of
           Perl ("compatibility" here being defined as sufficient  binary/"API"
           compatibility  to  run  "XS"  code  built  with  the older version).
           Normally this does not change across maintenance  releases.   Please
           read the comment in patchlevel.h.

       "PERL_API_VERSION"
           From patchlevel.h:

           This number describes the earliest compatible "PERL_VERSION" of Perl
           ("compatibility"  here  being  defined  as  sufficient  binary/"API"
           compatibility to run  "XS"  code  built  with  the  older  version).
           Normally  this  does not change across maintenance releases.  Please
           read the comment in patchlevel.h.

       "PERL_CONFIG_SH"
           From Oldsyms.U:

           This is set to "true" in config.sh so that a shell  script  sourcing
           config.sh can tell if it has been sourced already.

       "PERL_PATCHLEVEL"
           From Oldsyms.U:

           This symbol reflects the patchlevel, if available. Will usually come
           from  the  .patch file, which is available when the perl source tree
           was fetched with rsync.

       "PERL_REVISION"
           From Oldsyms.U:

           In a Perl version number such as 5.6.2, this is the 5.   This  value
           is manually set in patchlevel.h

       "PERL_SUBVERSION"
           From Oldsyms.U:

           In  a  Perl  version  number  such  as 5.6.2, this is the 2.  Values
           greater  than  50   represent   potentially   unstable   development
           subversions.  This value is manually set in patchlevel.h

       "PERL_VERSION"
           From Oldsyms.U:

           In  a  Perl version number such as 5.6.2, this is the 6.  This value
           is manually set in patchlevel.h

   _
       "_a"
           From Unix.U:

           This variable defines the extension used for ordinary library files.
           For unix, it is .a.  The  .  is  included.   Other  possible  values
           include .lib.

       "_exe"
           From Unix.U:

           This  variable  defines  the  extension  used  for executable files.
           "DJGPP", Cygwin and OS/2 use .exe.   Stratus  "VOS"  uses  .pm.   On
           operating  systems  which  do  not  require a specific extension for
           executable files, this variable is empty.

       "_o"
           From Unix.U:

           This variable defines the extension  used  for  object  files.   For
           unix,  it  is .o.  The . is included.  Other possible values include
           .obj.

   a
       "afs"
           From afs.U:

           This variable is set to "true" if "AFS" (Andrew File System) is used
           on the system, "false" otherwise.  It is possible to  override  this
           with a hint value or command line option, but you'd better know what
           you are doing.

       "afsroot"
           From afs.U:

           This  variable  is by default set to /afs. In the unlikely case this
           is not the correct root, it is possible to override this with a hint
           value or command line option.  This will be used in subsequent tests
           for AFSness in the configure and test process.

       "alignbytes"
           From alignbytes.U:

           This variable holds the number of bytes required to align a double--
           or a long double when applicable. Usual values are 2, 4 and 8.   The
           default is eight, for safety.

       "aphostname"
           From d_gethname.U:

           This  variable contains the command which can be used to compute the
           host name. The command is fully qualified by its absolute  path,  to
           make it safe when used by a process with super-user privileges.

       "api_revision"
           From patchlevel.U:

           The  three variables, api_revision, api_version, and api_subversion,
           specify the version of the oldest perl binary  compatible  with  the
           present  perl.  In a full version string such as 5.6.1, api_revision
           is the 5.  Prior to 5.5.640, the format was a floating point number,
           like 5.00563.

           perl.c:incpush()  and  lib/lib.pm  will  automatically   search   in
           $sitelib/..  for  older  directories  back to the limit specified by
           these api_ variables.  This is  only  useful  if  you  have  a  perl
           library  directory  tree  structured  like  the  default  one.   See
           "INSTALL" for how this works.  The versioned site_perl directory was
           introduced in 5.005, so that is  the  lowest  possible  value.   The
           version  list  appropriate  for  the current system is determined in
           inc_version_list.U.

           "XXX" To do:  Since compatibility can depend on compile time options
           (such as bincompat, longlong, etc.) it should (perhaps)  be  set  by
           Configure,  but currently it isn't.  Currently, we read a hard-wired
           value from patchlevel.h.  Perhaps what we ought to do  is  take  the
           hard-wired value from patchlevel.h but then modify it if the current
           Configure  options  warrant.   patchlevel.h then would use an #ifdef
           guard.

       "api_subversion"
           From patchlevel.U:

           The three variables, api_revision, api_version, and  api_subversion,
           specify  the  version  of the oldest perl binary compatible with the
           present  perl.   In  a  full   version   string   such   as   5.6.1,
           api_subversion is the 1.  See api_revision for full details.

       "api_version"
           From patchlevel.U:

           The  three variables, api_revision, api_version, and api_subversion,
           specify the version of the oldest perl binary  compatible  with  the
           present  perl.   In a full version string such as 5.6.1, api_version
           is the 6.  See api_revision for full details.  As  a  special  case,
           5.5.0  is  rendered  in  the  old-style  as 5.005.  (In the 5.005_0x
           maintenance  series,  this  was  the  only  versioned  directory  in
           $sitelib.)

       "api_versionstring"
           From patchlevel.U:

           This variable combines api_revision, api_version, and api_subversion
           in a format such as 5.6.1 (or 5_6_1) suitable for use as a directory
           name.  This is filesystem dependent.

       "ar"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the ar  program.   After  Configure  runs,  the
           value is reset to a plain "ar" and is not useful.

       "archlib"
           From archlib.U:

           This  variable  holds  the  name  of the directory in which the user
           wants  to  put  architecture-dependent  public  library  files   for
           $package.    It   is   most   often   a   local  directory  such  as
           /usr/local/lib.  Programs using this variable must  be  prepared  to
           deal with filename expansion.

       "archlibexp"
           From archlib.U:

           This  variable  is the same as the archlib variable, but is filename
           expanded at configuration time, for convenient use.

       "archname"
           From archname.U:

           This  variable  is  a  short  name  to  characterize   the   current
           architecture.  It is used mainly to construct the default archlib.

       "archname64"
           From use64bits.U:

           This variable is used for the 64-bitness part of $archname.

       "archobjs"
           From Unix.U:

           This  variable defines any additional objects that must be linked in
           with the program on this  architecture.   On  unix,  it  is  usually
           empty.   It is typically used to include emulations of unix calls or
           other facilities.  For perl on OS/2, for example, this would include
           os2/os2.obj.

       "asctime_r_proto"
           From d_asctime_r.U:

           This variable encodes the prototype of asctime_r.   It  is  zero  if
           d_asctime_r  is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_asctime_r is defined.

       "awk"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the awk program.  After Configure runs, the
           value is reset to a plain "awk" and is not useful.

   b
       "baserev"
           From baserev.U:

           The base revision level of this package, from the .package file.

       "bash"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "bin"
           From bin.U:

           This  variable  holds  the  name  of the directory in which the user
           wants to put publicly executable images for the package in question.
           It is most often a local directory such as /usr/local/bin.  Programs
           using   this   variable   must   be  prepared  to  deal  with  ~name
           substitution.

       "bin_ELF"
           From dlsrc.U:

           This variable saves the result from configure if generated  binaries
           are  in "ELF" format. Only set to defined when the test has actually
           been performed, and the result was positive.

       "binexp"
           From bin.U:

           This is the same as the bin variable, but is  filename  expanded  at
           configuration time, for use in your makefiles.

       "bison"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the bison program.  After Configure  runs,  the
           value is reset to a plain "bison" and is not useful.

       "byacc"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the byacc program.  After Configure  runs,  the
           value is reset to a plain "byacc" and is not useful.

       "byteorder"
           From byteorder.U:

           This  variable  holds  the  byte  order in a "UV". In the following,
           larger digits indicate more significance.  The variable byteorder is
           either 4321 on a big-endian machine, or 1234 on a little-endian,  or
           87654321 on a Cray ... or 3412 with weird order !

   c
       "c" From n.U:

           This variable contains the \c string if that is what causes the echo
           command  to  suppress newline.  Otherwise it is null.  Correct usage
           is $echo $n "prompt for a question: $c".

       "castflags"
           From d_castneg.U:

           This variable contains a flag that precise difficulties the compiler
           has casting odd floating values  to  unsigned  long:  0  =  ok  1  =
           couldn't  cast < 0 2 = couldn't cast >= 0x80000000 4 = couldn't cast
           in argument expression list

       "cat"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the cat program.  After Configure runs, the
           value is reset to a plain "cat" and is not useful.

       "cc"
           From cc.U:

           This variable holds the name of a command to execute  a  C  compiler
           which can resolve multiple global references that happen to have the
           same  name.   Usual  values  are  "cc"  and  "gcc".   Fervent "ANSI"
           compilers may be called "c89".  "AIX" has xlc.

       "cccdlflags"
           From dlsrc.U:

           This variable contains any special  flags  that  might  need  to  be
           passed with "cc -c" to compile modules to be used to create a shared
           library  that  will  be  used  for  dynamic loading.  For hpux, this
           should be +z.  It is up to the makefile to use it.

       "ccdlflags"
           From dlsrc.U:

           This variable contains any special  flags  that  might  need  to  be
           passed  to cc to link with a shared library for dynamic loading.  It
           is up to the makefile to use it.  For sunos 4.1, it should be empty.

       "ccflags"
           From ccflags.U:

           This variable contains any additional C compiler  flags  desired  by
           the user.  It is up to the Makefile to use this.

       "ccflags_uselargefiles"
           From uselfs.U:

           This  variable  contains  the  compiler  flags  needed by large file
           builds and added to ccflags by hints files.

       "ccname"
           From Checkcc.U:

           This can set either by hints files or by Configure.  If  using  gcc,
           this  is  gcc,  and  if  not, usually equal to cc, unimpressive, no?
           Some platforms, however, make good use of this by storing the flavor
           of the C compiler being used here.  For example  if  using  the  Sun
           WorkShop suite, ccname will be "workshop".

       "ccsymbols"
           From Cppsym.U:

           The  variable  contains the symbols defined by the C compiler alone.
           The symbols defined by cpp or by cc when it calls  cpp  are  not  in
           this  list,  see  cppsymbols and cppccsymbols.  The list is a space-
           separated list of symbol=value tokens.

       "ccversion"
           From Checkcc.U:

           This can set either by hints files or  by  Configure.   If  using  a
           (non-gcc)  vendor  cc,  this  variable may contain a version for the
           compiler.

       "cf_by"
           From cf_who.U:

           Login name of the person who ran the Configure script  and  answered
           the questions. This is used to tag both config.sh and config_h.SH.

       "cf_email"
           From cf_email.U:

           Electronic mail address of the person who ran Configure. This can be
           used by units that require the user's e-mail, like MailList.U.

       "cf_time"
           From cf_who.U:

           Holds  the  output of the "date" command when the configuration file
           was produced. This is used to tag both config.sh and config_h.SH.

       "charbits"
           From charsize.U:

           This variable contains the value of  the  "CHARBITS"  symbol,  which
           indicates to the C program how many bits there are in a character.

       "charsize"
           From charsize.U:

           This  variable  contains  the  value of the "CHARSIZE" symbol, which
           indicates to the C program how many bytes there are in a character.

       "chgrp"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "chmod"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the chmod program.  After Configure  runs,  the
           value is reset to a plain "chmod" and is not useful.

       "chown"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "clocktype"
           From d_times.U:

           This variable holds the type returned by times(). It can be long, or
           clock_t on "BSD"  sites  (in  which  case  <sys/types.h>  should  be
           included).

       "comm"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the comm program.  After  Configure  runs,  the
           value is reset to a plain "comm" and is not useful.

       "compiler_warning"
           From compiler_warning.U:

           This  variable holds the command to check if the file specified as a
           parameter contains a compiler warning

       "compress"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "config_arg0"
           From Options.U:

           This  variable  contains  the  string  used  to invoke the Configure
           command, as reported by the shell in the $0 variable.

       "config_argc"
           From Options.U:

           This variable contains the number of command-line  arguments  passed
           to  Configure,  as  reported  by  the shell in the $# variable.  The
           individual  arguments   are   stored   as   variables   config_arg1,
           config_arg2, etc.

       "config_args"
           From Options.U:

           This  variable  contains  a  single  string  giving the command-line
           arguments passed to Configure.     Spaces within arguments,  quotes,
           and  escaped characters are not correctly preserved.  To reconstruct
           the command line, you must  assemble  the  individual  command  line
           pieces, given in config_arg[0-9]*.

       "contains"
           From contains.U:

           This  variable  holds  the command to do a grep with a proper return
           status.  On most sane  systems  it  is  simply  "grep".   On  insane
           systems  it  is  a  grep followed by a cat followed by a test.  This
           variable is primarily for the use of other Configure units.

       "cp"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the  cp program.  After Configure runs, the
           value is reset to a plain "cp" and is not useful.

       "cpio"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "cpp"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the cpp program.   After  Configure  runs,  the
           value is reset to a plain "cpp" and is not useful.

       "cpp_stuff"
           From cpp_stuff.U:

           This  variable  contains  an  identification  of  the  concatenation
           mechanism used by the C preprocessor.

       "cppccsymbols"
           From Cppsym.U:

           The variable contains the symbols defined by the C compiler when  it
           calls cpp.  The symbols defined by the cc alone or cpp alone are not
           in  this  list,  see ccsymbols and cppsymbols.  The list is a space-
           separated list of symbol=value tokens.

       "cppflags"
           From ccflags.U:

           This variable holds the flags that will be  passed  to  the  C  pre-
           processor. It is up to the Makefile to use it.

       "cpplast"
           From cppstdin.U:

           This  variable  has  the  same  functionality  as  cppminus, only it
           applies to cpprun and not cppstdin.

       "cppminus"
           From cppstdin.U:

           This variable contains the second part  of  the  string  which  will
           invoke  the  C  preprocessor  on  the  standard input and produce to
           standard output.  This variable will have the value "-" if  cppstdin
           needs a minus to specify standard input, otherwise the value is "".

       "cpprun"
           From cppstdin.U:

           This   variable   contains   the  command  which  will  invoke  a  C
           preprocessor on standard input and put the output to stdout.  It  is
           guaranteed  not  to  be  a  wrapper  and  may be a null string if no
           preprocessor can be made directly available. This preprocessor might
           be different from the one used by the C compiler.  Don't  forget  to
           append cpplast after the preprocessor options.

       "cppstdin"
           From cppstdin.U:

           This   variable  contains  the  command  which  will  invoke  the  C
           preprocessor on standard input and put the output to stdout.  It  is
           primarily  used by other Configure units that ask about preprocessor
           symbols.

       "cppsymbols"
           From Cppsym.U:

           The variable contains the symbols  defined  by  the  C  preprocessor
           alone.  The symbols defined by cc or by cc when it calls cpp are not
           in  this list, see ccsymbols and cppccsymbols.  The list is a space-
           separated list of symbol=value tokens.

       "crypt_r_proto"
           From d_crypt_r.U:

           This variable encodes the prototype  of  crypt_r.   It  is  zero  if
           d_crypt_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of
           reentr.h if d_crypt_r is defined.

       "cryptlib"
           From d_crypt.U:

           This  variable  holds -lcrypt or the path to a libcrypt.a archive if
           the crypt() function is not defined in the standard C library. It is
           up to the Makefile to use this.

       "csh"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the csh program.  After Configure runs, the
           value is reset to a plain "csh" and is not useful.

       "ctermid_r_proto"
           From d_ctermid_r.U:

           This variable encodes the prototype of ctermid_r.   It  is  zero  if
           d_ctermid_r  is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_ctermid_r is defined.

       "ctime_r_proto"
           From d_ctime_r.U:

           This variable encodes the prototype  of  ctime_r.   It  is  zero  if
           d_ctime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of
           reentr.h if d_ctime_r is defined.

   d
       "d_Gconvert"
           From d_gconvert.U:

           This  variable holds what Gconvert is defined as to convert floating
           point numbers into strings.  By default, Configure sets "this" macro
           to  use  the  first  of  gconvert,  gcvt,  or  sprintf   that   pass
           sprintf-%g-like  behavior tests.  If perl is using long doubles, the
           macro  uses  the  first  of  the  following  functions   that   pass
           Configure's  tests:  qgcvt,  sprintf (if Configure knows how to make
           sprintf format long doubles--see  sPRIgldbl),  gconvert,  gcvt,  and
           sprintf   (casting   to   double).    The   gconvert_preference  and
           gconvert_ld_preference variables can be used  to  alter  Configure's
           preferences,   for  doubles  and  long  doubles,  respectively.   If
           present, they contain a space-separated list of one or more  of  the
           above function names in the order they should be tried.

           d_Gconvert  may  be  set  to  override  Configure  with  a platform-
           specific function.  If this function expects a double,  a  different
           value  may need to be set by the uselongdouble.cbu call-back unit so
           that long doubles can be formatted without loss of precision.

       "d_PRIEUldbl"
           From longdblfio.U:

           This variable conditionally defines the PERL_PRIfldbl symbol,  which
           indicates that stdio has a symbol to print long doubles.  The "U" in
           the name is to separate this from d_PRIeldbl so that even case-blind
           systems can see the difference.

       "d_PRIFUldbl"
           From longdblfio.U:

           This  variable conditionally defines the PERL_PRIfldbl symbol, which
           indicates that stdio has a symbol to print long doubles.  The "U" in
           the name is to separate this from d_PRIfldbl so that even case-blind
           systems can see the difference.

       "d_PRIGUldbl"
           From longdblfio.U:

           This variable conditionally defines the PERL_PRIfldbl symbol,  which
           indicates that stdio has a symbol to print long doubles.  The "U" in
           the name is to separate this from d_PRIgldbl so that even case-blind
           systems can see the difference.

       "d_PRIXU64"
           From quadfio.U:

           This  variable  conditionally defines the PERL_PRIXU64 symbol, which
           indicates that stdio  has  a  symbol  to  print  64-bit  hExADECimAl
           numbers.   The  "U" in the name is to separate this from d_PRIx64 so
           that even case-blind systems can see the difference.

       "d_PRId64"
           From quadfio.U:

           This variable conditionally defines the  PERL_PRId64  symbol,  which
           indicates that stdio has a symbol to print 64-bit decimal numbers.

       "d_PRIeldbl"
           From longdblfio.U:

           This  variable conditionally defines the PERL_PRIfldbl symbol, which
           indicates that stdio has a symbol to print long doubles.

       "d_PRIfldbl"
           From longdblfio.U:

           This variable conditionally defines the PERL_PRIfldbl symbol,  which
           indicates that stdio has a symbol to print long doubles.

       "d_PRIgldbl"
           From longdblfio.U:

           This  variable conditionally defines the PERL_PRIfldbl symbol, which
           indicates that stdio has a symbol to print long doubles.

       "d_PRIi64"
           From quadfio.U:

           This variable conditionally defines the  PERL_PRIi64  symbol,  which
           indicates that stdio has a symbol to print 64-bit decimal numbers.

       "d_PRIo64"
           From quadfio.U:

           This  variable  conditionally  defines the PERL_PRIo64 symbol, which
           indicates that stdio has a symbol to print 64-bit octal numbers.

       "d_PRIu64"
           From quadfio.U:

           This variable conditionally defines the  PERL_PRIu64  symbol,  which
           indicates  that  stdio has a symbol to print 64-bit unsigned decimal
           numbers.

       "d_PRIx64"
           From quadfio.U:

           This variable conditionally defines the  PERL_PRIx64  symbol,  which
           indicates  that  stdio  has  a  symbol  to  print 64-bit hexadecimal
           numbers.

       "d_SCNfldbl"
           From longdblfio.U:

           This variable conditionally defines the PERL_PRIfldbl symbol,  which
           indicates that stdio has a symbol to scan long doubles.

       "d__fwalk"
           From d__fwalk.U:

           This  variable  conditionally  defines  "HAS__FWALK"  if _fwalk() is
           available to apply a function to all the file handles.

       "d_accept4"
           From d_accept4.U:

           This variable conditionally  defines  HAS_ACCEPT4  if  accept4()  is
           available to accept socket connections.

       "d_access"
           From d_access.U:

           This  variable  conditionally  defines  "HAS_ACCESS" if the access()
           system call is available to check for access permissions using  real
           IDs.

       "d_accessx"
           From d_accessx.U:

           This  variable conditionally defines the "HAS_ACCESSX" symbol, which
           indicates to the C program that the accessx() routine is available.

       "d_acosh"
           From d_acosh.U:

           This variable conditionally defines the  "HAS_ACOSH"  symbol,  which
           indicates to the C program that the acosh() routine is available.

       "d_aintl"
           From d_aintl.U:

           This  variable  conditionally  defines the "HAS_AINTL" symbol, which
           indicates to the C program that the aintl()  routine  is  available.
           If copysignl is also present we can emulate modfl.

       "d_alarm"
           From d_alarm.U:

           This  variable  conditionally  defines the "HAS_ALARM" symbol, which
           indicates to the C program that the alarm() routine is available.

       "d_archlib"
           From archlib.U:

           This variable conditionally defines "ARCHLIB" to hold  the  pathname
           of  architecture-dependent  library files for $package.  If $archlib
           is the same as $privlib, then this is set to undef.

       "d_asctime64"
           From d_timefuncs64.U:

           This variable conditionally defines the HAS_ASCTIME64 symbol,  which
           indicates  to  the  C  program  that  the  asctime64  ()  routine is
           available.

       "d_asctime_r"
           From d_asctime_r.U:

           This variable  conditionally  defines  the  "HAS_ASCTIME_R"  symbol,
           which  indicates  to  the  C program that the asctime_r() routine is
           available.

       "d_asinh"
           From d_asinh.U:

           This variable conditionally defines the  "HAS_ASINH"  symbol,  which
           indicates to the C program that the asinh() routine is available.

       "d_atanh"
           From d_atanh.U:

           This  variable  conditionally  defines the "HAS_ATANH" symbol, which
           indicates to the C program that the atanh() routine is available.

       "d_atolf"
           From atolf.U:

           This variable conditionally defines the  "HAS_ATOLF"  symbol,  which
           indicates to the C program that the atolf() routine is available.

       "d_atoll"
           From atoll.U:

           This  variable  conditionally  defines the "HAS_ATOLL" symbol, which
           indicates to the C program that the atoll() routine is available.

       "d_attribute_always_inline"
           From d_attribut.U:

           This variable  conditionally  defines  "HASATTRIBUTE_ALWAYS_INLINE",
           which  indicates that the C compiler can know that certain functions
           should always be inlined.

       "d_attribute_deprecated"
           From d_attribut.U:

           This variable conditionally defines "HASATTRIBUTE_DEPRECATED", which
           indicates that "GCC" can handle the attribute for marking deprecated
           APIs

       "d_attribute_format"
           From d_attribut.U:

           This variable  conditionally  defines  "HASATTRIBUTE_FORMAT",  which
           indicates the C compiler can check for printf-like formats.

       "d_attribute_malloc"
           From d_attribut.U:

           This  variable  conditionally  defines  "HASATTRIBUTE_MALLOC", which
           indicates the C compiler can understand functions as having  malloc-
           like semantics.

       "d_attribute_nonnull"
           From d_attribut.U:

           This  variable  conditionally  defines "HASATTRIBUTE_NONNULL", which
           indicates that the C compiler can know that certain  arguments  must
           not be "NULL", and will check accordingly at compile time.

       "d_attribute_noreturn"
           From d_attribut.U:

           This  variable  conditionally defines "HASATTRIBUTE_NORETURN", which
           indicates that the C compiler can know that  certain  functions  are
           guaranteed never to return.

       "d_attribute_pure"
           From d_attribut.U:

           This   variable  conditionally  defines  "HASATTRIBUTE_PURE",  which
           indicates that the C compiler can know that  certain  functions  are
           "pure"  functions,  meaning that they have no side effects, and only
           rely on function input and/or global data for their results.

       "d_attribute_unused"
           From d_attribut.U:

           This variable  conditionally  defines  "HASATTRIBUTE_UNUSED",  which
           indicates  that  the  C compiler can know that certain variables and
           arguments may not always be used, and to not throw warnings if  they
           don't get used.

       "d_attribute_visibility"
           From d_attribut.U:

           This  variable  conditionally  defines the "HASATTRIBUTE_VISIBILITY"
           symbol, and indicates different "GCC" attribute visibility

       "d_attribute_warn_unused_result"
           From d_attribut.U:

           This            variable            conditionally            defines
           "HASATTRIBUTE_WARN_UNUSED_RESULT",   which   indicates  that  the  C
           compiler can know that certain functions have a return  values  that
           must not be ignored, such as malloc() or open().

       "d_backtrace"
           From d_backtrace.U:

           This  variable  conditionally  defines  the  "HAS_BACKTRACE" symbol,
           which indicates to the C program that  the  backtrace()  routine  is
           available to get a stack trace.

       "d_bsd"
           From Guess.U:

           This symbol conditionally defines the symbol "BSD" when running on a
           "BSD" system.

       "d_bsdgetpgrp"
           From d_getpgrp.U:

           This  variable  conditionally  defines  "USE_BSD_GETPGRP" if getpgrp
           needs one arguments whereas "USG" one needs none.

       "d_bsdsetpgrp"
           From d_setpgrp.U:

           This variable conditionally  defines  "USE_BSD_SETPGRP"  if  setpgrp
           needs  two  arguments  whereas  "USG"  one  needs  none.   See  also
           d_setpgid for a "POSIX" interface.

       "d_builtin_add_overflow"
           From d_builtin_overflow.U:

           This  variable  conditionally  defines   "HAS_BUILTIN_ADD_OVERFLOW",
           which       indicates      that      the      compiler      supports
           __builtin_add_overflow(x,y,&z) for safely adding  x  and  y  into  z
           while checking for overflow.

       "d_builtin_choose_expr"
           From d_builtin.U:

           This    conditionally   defines   "HAS_BUILTIN_CHOOSE_EXPR",   which
           indicates that the compiler  supports  __builtin_choose_expr(x,y,z).
           This  built-in  function  is analogous to the "x?y:z" operator in C,
           except that the  expression  returned  has  its  type  unaltered  by
           promotion  rules.  Also, the built-in function does not evaluate the
           expression that was not chosen.

       "d_builtin_expect"
           From d_builtin.U:

           This conditionally  defines  "HAS_BUILTIN_EXPECT",  which  indicates
           that  the  compiler  supports  __builtin_expect(exp,c).  You may use
           __builtin_expect to provide  the  compiler  with  branch  prediction
           information.

       "d_builtin_mul_overflow"
           From d_builtin_overflow.U:

           This   variable  conditionally  defines  "HAS_BUILTIN_MUL_OVERFLOW",
           which      indicates      that      the      compiler       supports
           __builtin_mul_overflow(x,y,&z) for safely multiplying x and y into z
           while checking for overflow.

       "d_builtin_sub_overflow"
           From d_builtin_overflow.U:

           This   variable  conditionally  defines  "HAS_BUILTIN_SUB_OVERFLOW",
           which      indicates      that      the      compiler       supports
           __builtin_sub_overflow(x,y,&z)  for safely subtracting y from x into
           z while checking for overflow.

       "d_c99_variadic_macros"
           From d_c99_variadic.U:

           This  variable  conditionally  defines  the  HAS_C99_VARIADIC_MACROS
           symbol,  which  indicates  to the C program that C99 variadic macros
           are available.

       "d_casti32"
           From d_casti32.U:

           This variable conditionally defines CASTI32, which indicates whether
           the C compiler can cast large floats to 32-bit ints.

       "d_castneg"
           From d_castneg.U:

           This  variable  conditionally  defines  "CASTNEG",  which  indicates
           whether the C compiler can cast negative float to unsigned.

       "d_cbrt"
           From d_cbrt.U:

           This  variable  conditionally  defines  the "HAS_CBRT" symbol, which
           indicates to the C program that the cbrt() (cube root)  function  is
           available.

       "d_chown"
           From d_chown.U:

           This  variable  conditionally  defines the "HAS_CHOWN" symbol, which
           indicates to the C program that the chown() routine is available.

       "d_chroot"
           From d_chroot.U:

           This variable conditionally defines the "HAS_CHROOT"  symbol,  which
           indicates to the C program that the chroot() routine is available.

       "d_chsize"
           From d_chsize.U:

           This  variable  conditionally  defines  the  "CHSIZE"  symbol, which
           indicates to the C program that the chsize() routine is available to
           truncate files.  You might need a -lx to get this routine.

       "d_class"
           From d_class.U:

           This variable conditionally defines the  "HAS_CLASS"  symbol,  which
           indicates to the C program that the class() routine is available.

       "d_clearenv"
           From d_clearenv.U:

           This variable conditionally defines the "HAS_CLEARENV" symbol, which
           indicates  to  the  C  program  that  the  clearenv  ()  routine  is
           available.

       "d_closedir"
           From d_closedir.U:

           This variable conditionally defines "HAS_CLOSEDIR" if closedir()  is
           available.

       "d_cmsghdr_s"
           From d_cmsghdr_s.U:

           This variable conditionally defines the "HAS_STRUCT_CMSGHDR" symbol,
           which indicates that the struct cmsghdr is supported.

       "d_copysign"
           From d_copysign.U:

           This variable conditionally defines the "HAS_COPYSIGN" symbol, which
           indicates to the C program that the copysign() routine is available.

       "d_copysignl"
           From d_copysignl.U:

           This  variable  conditionally  defines  the  "HAS_COPYSIGNL" symbol,
           which indicates to the C program that  the  copysignl()  routine  is
           available.  If aintl is also present we can emulate modfl.

       "d_cplusplus"
           From d_cplusplus.U:

           This  variable  conditionally  defines  the  "USE_CPLUSPLUS" symbol,
           which indicates that a C++ compiler was used to  compiled  Perl  and
           will be used to compile extensions.

       "d_crypt"
           From d_crypt.U:

           This  variable  conditionally  defines  the  "CRYPT"  symbol,  which
           indicates to the C program that the crypt() routine is available  to
           encrypt passwords and the like.

       "d_crypt_r"
           From d_crypt_r.U:

           This  variable conditionally defines the "HAS_CRYPT_R" symbol, which
           indicates to the C program that the crypt_r() routine is available.

       "d_csh"
           From d_csh.U:

           This  variable  conditionally  defines  the  "CSH"   symbol,   which
           indicates to the C program that the C-shell exists.

       "d_ctermid"
           From d_ctermid.U:

           This  variable  conditionally  defines  "CTERMID"  if  ctermid()  is
           available to generate filename for terminal.

       "d_ctermid_r"
           From d_ctermid_r.U:

           This variable  conditionally  defines  the  "HAS_CTERMID_R"  symbol,
           which  indicates  to  the  C program that the ctermid_r() routine is
           available.

       "d_ctime64"
           From d_timefuncs64.U:

           This variable conditionally defines the  HAS_CTIME64  symbol,  which
           indicates to the C program that the ctime64 () routine is available.

       "d_ctime_r"
           From d_ctime_r.U:

           This  variable conditionally defines the "HAS_CTIME_R" symbol, which
           indicates to the C program that the ctime_r() routine is available.

       "d_cuserid"
           From d_cuserid.U:

           This variable conditionally defines the "HAS_CUSERID" symbol,  which
           indicates  to  the C program that the cuserid() routine is available
           to get character login names.

       "d_dbminitproto"
           From d_dbminitproto.U:

           This variable conditionally defines the "HAS_DBMINIT_PROTO"  symbol,
           which  indicates  to  the  C  program  that  the  system  provides a
           prototype for the dbminit() function.  Otherwise, it is  up  to  the
           program to supply one.

       "d_difftime"
           From d_difftime.U:

           This variable conditionally defines the "HAS_DIFFTIME" symbol, which
           indicates to the C program that the difftime() routine is available.

       "d_difftime64"
           From d_timefuncs64.U:

           This variable conditionally defines the HAS_DIFFTIME64 symbol, which
           indicates  to  the  C  program  that  the  difftime64  () routine is
           available.

       "d_dir_dd_fd"
           From d_dir_dd_fd.U:

           This variable  conditionally  defines  the  "HAS_DIR_DD_FD"  symbol,
           which  indicates  that  the  "DIR"  directory stream type contains a
           member variable called dd_fd.

       "d_dirfd"
           From d_dirfd.U:

           This variable conditionally defines the "HAS_DIRFD" constant,  which
           indicates  to  the C program that dirfd() is available to return the
           file descriptor of a directory stream.

       "d_dirnamlen"
           From i_dirent.U:

           This variable conditionally defines "DIRNAMLEN", which indicates  to
           the  C  program that the length of directory entry names is provided
           by a d_namelen field.

       "d_dladdr"
           From d_dladdr.U:

           This variable conditionally defines the "HAS_DLADDR"  symbol,  which
           indicates to the C program that the dladdr() routine is available to
           get a stack trace.

       "d_dlerror"
           From d_dlerror.U:

           This  variable conditionally defines the "HAS_DLERROR" symbol, which
           indicates to the C program that the dlerror() routine is available.

       "d_dlopen"
           From d_dlopen.U:

           This variable conditionally defines the "HAS_DLOPEN"  symbol,  which
           indicates to the C program that the dlopen() routine is available.

       "d_dlsymun"
           From d_dlsymun.U:

           This  variable conditionally defines "DLSYM_NEEDS_UNDERSCORE", which
           indicates that we need to prepend an underscore to the  symbol  name
           before calling dlsym().

       "d_dosuid"
           From d_dosuid.U:

           This variable conditionally defines the symbol "DOSUID", which tells
           the  C  program that it should insert setuid emulation code on hosts
           which have setuid #! scripts disabled.

       "d_double_has_inf"
           From longdblfio.U:

           This variable  conditionally  defines  the  symbol  "DOUBLE_HAS_INF"
           which indicates that the double type has an infinity.

       "d_double_has_nan"
           From longdblfio.U:

           This  variable  conditionally  defines  the  symbol "DOUBLE_HAS_NAN"
           which indicates that the double type has a not-a-number.

       "d_double_has_negative_zero"
           From longdblfio.U:

           This     variable     conditionally     defines      the      symbol
           "DOUBLE_HAS_NEGATIVE_ZERO"  which indicates that the double type has
           a negative zero.

       "d_double_has_subnormals"
           From longdblfio.U:

           This     variable     conditionally     defines      the      symbol
           "DOUBLE_HAS_SUBNORMALS"  which  indicates  that  the double type has
           subnormals (denormals).

       "d_double_style_cray"
           From longdblfio.U:

           This variable conditionally defines the  symbol  "DOUBLE_STYLE_CRAY"
           which  indicates  that  the  double  is  the 64-bit "CRAY" mainframe
           format.

       "d_double_style_ibm"
           From longdblfio.U:

           This variable conditionally defines the  symbol  "DOUBLE_STYLE_IBM",
           which  indicates  that  the  double  is  the  64-bit "IBM" mainframe
           format.

       "d_double_style_ieee"
           From longdblfio.U:

           This variable conditionally defines the symbol  "DOUBLE_STYLE_IEEE",
           which indicates that the double is the 64-bit "IEEE" 754.

       "d_double_style_vax"
           From longdblfio.U:

           This  variable  conditionally defines the symbol "DOUBLE_STYLE_VAX",
           which indicates that the double is the 64-bit "VAX" format D or G.

       "d_drand48_r"
           From d_drand48_r.U:

           This variable conditionally defines the HAS_DRAND48_R symbol,  which
           indicates   to  the  C  program  that  the  drand48_r()  routine  is
           available.

       "d_drand48proto"
           From d_drand48proto.U:

           This variable conditionally defines  the  HAS_DRAND48_PROTO  symbol,
           which  indicates  to  the  C  program  that  the  system  provides a
           prototype for the drand48() function.  Otherwise, it is  up  to  the
           program to supply one.

       "d_dup2"
           From d_dup2.U:

           This  variable conditionally defines HAS_DUP2 if dup2() is available
           to duplicate file descriptors.

       "d_dup3"
           From d_dup3.U:

           This variable conditionally defines HAS_DUP3 if dup3() is  available
           to duplicate file descriptors.

       "d_duplocale"
           From d_newlocale.U:

           This  variable  conditionally  defines  the  "HAS_DUPLOCALE" symbol,
           which indicates to the C program that  the  duplocale()  routine  is
           available to duplicate a locale object.

       "d_eaccess"
           From d_eaccess.U:

           This  variable conditionally defines the "HAS_EACCESS" symbol, which
           indicates to the C program that the eaccess() routine is available.

       "d_endgrent"
           From d_endgrent.U:

           This variable conditionally defines the "HAS_ENDGRENT" symbol, which
           indicates to the C program that the endgrent() routine is  available
           for sequential access of the group database.

       "d_endgrent_r"
           From d_endgrent_r.U:

           This  variable  conditionally  defines  the "HAS_ENDGRENT_R" symbol,
           which indicates to the C program that the  endgrent_r()  routine  is
           available.

       "d_endhent"
           From d_endhent.U:

           This variable conditionally defines "HAS_ENDHOSTENT" if endhostent()
           is available to close whatever was being used for host queries.

       "d_endhostent_r"
           From d_endhostent_r.U:

           This  variable  conditionally defines the "HAS_ENDHOSTENT_R" symbol,
           which indicates to the C program that the endhostent_r() routine  is
           available.

       "d_endnent"
           From d_endnent.U:

           This  variable  conditionally defines "HAS_ENDNETENT" if endnetent()
           is available to close whatever was being used for network queries.

       "d_endnetent_r"
           From d_endnetent_r.U:

           This variable conditionally defines  the  "HAS_ENDNETENT_R"  symbol,
           which  indicates  to the C program that the endnetent_r() routine is
           available.

       "d_endpent"
           From d_endpent.U:

           This   variable   conditionally   defines    "HAS_ENDPROTOENT"    if
           endprotoent()  is  available  to  close  whatever was being used for
           protocol queries.

       "d_endprotoent_r"
           From d_endprotoent_r.U:

           This variable conditionally defines the "HAS_ENDPROTOENT_R"  symbol,
           which indicates to the C program that the endprotoent_r() routine is
           available.

       "d_endpwent"
           From d_endpwent.U:

           This variable conditionally defines the "HAS_ENDPWENT" symbol, which
           indicates  to the C program that the endpwent() routine is available
           for sequential access of the passwd database.

       "d_endpwent_r"
           From d_endpwent_r.U:

           This variable conditionally  defines  the  "HAS_ENDPWENT_R"  symbol,
           which  indicates  to  the C program that the endpwent_r() routine is
           available.

       "d_endsent"
           From d_endsent.U:

           This variable conditionally defines "HAS_ENDSERVENT" if endservent()
           is available to close whatever was being used for service queries.

       "d_endservent_r"
           From d_endservent_r.U:

           This variable conditionally defines the  "HAS_ENDSERVENT_R"  symbol,
           which  indicates to the C program that the endservent_r() routine is
           available.

       "d_eofnblk"
           From nblock_io.U:

           This variable conditionally defines "EOF_NONBLOCK" if "EOF"  can  be
           seen when reading from a non-blocking I/O source.

       "d_erf"
           From d_erf.U:

           This  variable  conditionally  defines  the  "HAS_ERF" symbol, which
           indicates to the C program that the erf() routine is available.

       "d_erfc"
           From d_erfc.U:

           This variable conditionally defines  the  "HAS_ERFC"  symbol,  which
           indicates to the C program that the erfc() routine is available.

       "d_eunice"
           From Guess.U:

           This  variable conditionally defines the symbols "EUNICE" and "VAX",
           which alerts the C program that it must deal with idiosyncrasies  of
           "VMS".

       "d_exp2"
           From d_exp2.U:

           This  variable  conditionally  defines  the  HAS_EXP2  symbol, which
           indicates to the C program that the exp2() routine is available.

       "d_expm1"
           From d_expm1.U:

           This variable conditionally  defines  the  HAS_EXPM1  symbol,  which
           indicates to the C program that the expm1() routine is available.

       "d_faststdio"
           From d_faststdio.U:

           This  variable  conditionally  defines  the "HAS_FAST_STDIO" symbol,
           which indicates to the C program that the "fast stdio" is  available
           to manipulate the stdio buffers directly.

       "d_fchdir"
           From d_fchdir.U:

           This  variable  conditionally defines the "HAS_FCHDIR" symbol, which
           indicates to the C program that the fchdir() routine is available.

       "d_fchmod"
           From d_fchmod.U:

           This variable conditionally defines the "HAS_FCHMOD"  symbol,  which
           indicates to the C program that the fchmod() routine is available to
           change mode of opened files.

       "d_fchmodat"
           From d_fsat.U:

           This variable conditionally defines the "HAS_FCHMODAT" symbol, which
           indicates the "POSIX" fchmodat() function is available.

       "d_fchown"
           From d_fchown.U:

           This  variable  conditionally defines the "HAS_FCHOWN" symbol, which
           indicates to the C program that the fchown() routine is available to
           change ownership of opened files.

       "d_fcntl"
           From d_fcntl.U:

           This variable conditionally  defines  the  "HAS_FCNTL"  symbol,  and
           indicates whether the fcntl() function exists

       "d_fcntl_can_lock"
           From d_fcntl_can_lock.U:

           This  variable conditionally defines the "FCNTL_CAN_LOCK" symbol and
           indicates whether file locking with fcntl() works.

       "d_fd_macros"
           From d_fd_set.U:

           This variable contains the eventual  value  of  the  "HAS_FD_MACROS"
           symbol,  which  indicates  if your C compiler knows about the macros
           which manipulate an fd_set.

       "d_fd_set"
           From d_fd_set.U:

           This variable  contains  the  eventual  value  of  the  "HAS_FD_SET"
           symbol,  which  indicates  if your C compiler knows about the fd_set
           typedef.

       "d_fdclose"
           From d_fdclose.U:

           This variable conditionally defines the "HAS_FDCLOSE" symbol,  which
           indicates to the C program that the fdclose() routine is available.

       "d_fdim"
           From d_fdim.U:

           This  variable  conditionally  defines  the "HAS_FDIM" symbol, which
           indicates to the C program that the fdim() routine is available.

       "d_fdopendir"
           From d_fdopendir.U:

           This variable conditionally defines  the  "HAS_FORK"  symbol,  which
           indicates  that  the fdopen routine is available to open a directory
           descriptor.

       "d_fds_bits"
           From d_fd_set.U:

           This variable contains the  eventual  value  of  the  "HAS_FDS_BITS"
           symbol, which indicates if your fd_set typedef contains the fds_bits
           member.  If you have an fd_set typedef, but the dweebs who installed
           it  did  a  half-fast  job  and  neglected  to provide the macros to
           manipulate an fd_set, "HAS_FDS_BITS" will let us know how to fix the
           gaffe.

       "d_fegetround"
           From d_fegetround.U:

           This variable conditionally defines "HAS_FEGETROUND" if fegetround()
           is available to get the floating point rounding mode.

       "d_ffs"
           From d_ffs.U:

           This variable conditionally  defines  the  "HAS_FFS"  symbol,  which
           indicates  to  the  C program that the ffs() routine is available to
           find the first bit which is set in its integer argument.

       "d_ffsl"
           From d_ffs.U:

           This variable conditionally defines  the  "HAS_FFSL"  symbol,  which
           indicates  to  the C program that the ffsl() routine is available to
           find the first bit which is set in its long integer argument.

       "d_fgetpos"
           From d_fgetpos.U:

           This variable conditionally defines "HAS_FGETPOS"  if  fgetpos()  is
           available to get the file position indicator.

       "d_finite"
           From d_finite.U:

           This  variable  conditionally defines the "HAS_FINITE" symbol, which
           indicates to the C program that the finite() routine is available.

       "d_finitel"
           From d_finitel.U:

           This variable conditionally defines the "HAS_FINITEL" symbol,  which
           indicates to the C program that the finitel() routine is available.

       "d_flexfnam"
           From d_flexfnam.U:

           This  variable  conditionally  defines  the  "FLEXFILENAMES" symbol,
           which indicates that the system supports filenames  longer  than  14
           characters.

       "d_flock"
           From d_flock.U:

           This  variable  conditionally  defines  "HAS_FLOCK"  if  flock()  is
           available to do file locking.

       "d_flockproto"
           From d_flockproto.U:

           This variable conditionally defines  the  "HAS_FLOCK_PROTO"  symbol,
           which  indicates  to  the  C  program  that  the  system  provides a
           prototype for the flock() function.  Otherwise,  it  is  up  to  the
           program to supply one.

       "d_fma"
           From d_fma.U:

           This  variable  conditionally  defines  the  "HAS_FMA" symbol, which
           indicates to the C program that the fma() routine is available.

       "d_fmax"
           From d_fmax.U:

           This variable conditionally defines  the  "HAS_FMAX"  symbol,  which
           indicates to the C program that the fmax() routine is available.

       "d_fmin"
           From d_fmin.U:

           This  variable  conditionally  defines  the "HAS_FMIN" symbol, which
           indicates to the C program that the fmin() routine is available.

       "d_fork"
           From d_fork.U:

           This variable conditionally defines  the  "HAS_FORK"  symbol,  which
           indicates to the C program that the fork() routine is available.

       "d_fp_class"
           From d_fp_class.U:

           This variable conditionally defines the "HAS_FP_CLASS" symbol, which
           indicates to the C program that the fp_class() routine is available.

       "d_fp_classify"
           From d_fpclassify.U:

           This  variable  conditionally  defines the "HAS_FP_CLASSIFY" symbol,
           which indicates to the C program that the fp_classify()  routine  is
           available.

       "d_fp_classl"
           From d_fp_classl.U:

           This  variable  conditionally  defines  the  "HAS_FP_CLASSL" symbol,
           which indicates to the C program that  the  fp_classl()  routine  is
           available.

       "d_fpathconf"
           From d_pathconf.U:

           This  variable  conditionally  defines  the  "HAS_FPATHCONF" symbol,
           which indicates to the C program  that  the  pathconf()  routine  is
           available  to  determine  file-system  related  limits  and  options
           associated with a given open file descriptor.

       "d_fpclass"
           From d_fpclass.U:

           This variable conditionally defines the "HAS_FPCLASS" symbol,  which
           indicates to the C program that the fpclass() routine is available.

       "d_fpclassify"
           From d_fpclassify.U:

           This  variable  conditionally  defines  the "HAS_FPCLASSIFY" symbol,
           which indicates to the C program that the  fpclassify()  routine  is
           available.

       "d_fpclassl"
           From d_fpclassl.U:

           This variable conditionally defines the "HAS_FPCLASSL" symbol, which
           indicates to the C program that the fpclassl() routine is available.

       "d_fpgetround"
           From d_fpgetround.U:

           This variable conditionally defines "HAS_FPGETROUND" if fpgetround()
           is available to get the floating point rounding mode.

       "d_fpos64_t"
           From d_fpos64_t.U:

           This symbol will be defined if the C compiler supports fpos64_t.

       "d_freelocale"
           From d_newlocale.U:

           This  variable  conditionally  defines  the "HAS_FREELOCALE" symbol,
           which indicates to the C program that the  freelocale()  routine  is
           available  to  deallocates  the  resources  associated with a locale
           object.

       "d_frexpl"
           From d_frexpl.U:

           This variable conditionally defines the "HAS_FREXPL"  symbol,  which
           indicates to the C program that the frexpl() routine is available.

       "d_fs_data_s"
           From d_fs_data_s.U:

           This variable conditionally defines the "HAS_STRUCT_FS_DATA" symbol,
           which indicates that the struct fs_data is supported.

       "d_fseeko"
           From d_fseeko.U:

           This  variable  conditionally defines the "HAS_FSEEKO" symbol, which
           indicates to the C program that the fseeko() routine is available.

       "d_fsetpos"
           From d_fsetpos.U:

           This variable conditionally defines "HAS_FSETPOS"  if  fsetpos()  is
           available to set the file position indicator.

       "d_fstatfs"
           From d_fstatfs.U:

           This  variable conditionally defines the "HAS_FSTATFS" symbol, which
           indicates to the C program that the fstatfs() routine is available.

       "d_fstatvfs"
           From d_statvfs.U:

           This variable conditionally defines the "HAS_FSTATVFS" symbol, which
           indicates to the C program that the fstatvfs() routine is available.

       "d_fsync"
           From d_fsync.U:

           This variable conditionally defines the  "HAS_FSYNC"  symbol,  which
           indicates to the C program that the fsync() routine is available.

       "d_ftello"
           From d_ftello.U:

           This  variable  conditionally defines the "HAS_FTELLO" symbol, which
           indicates to the C program that the ftello() routine is available.

       "d_ftime"
           From d_ftime.U:

           This variable conditionally defines the  "HAS_FTIME"  symbol,  which
           indicates  that  the ftime() routine exists.  The ftime() routine is
           basically a sub-second accuracy clock.

       "d_futimes"
           From d_futimes.U:

           This variable conditionally defines the "HAS_FUTIMES" symbol,  which
           indicates to the C program that the futimes() routine is available.

       "d_gai_strerror"
           From d_gai_strerror.U:

           This variable conditionally defines the "HAS_GAI_STRERROR" symbol if
           the gai_strerror() routine is available and can be used to translate
           error codes returned by getaddrinfo() into human readable strings.

       "d_gdbm_ndbm_h_uses_prototypes"
           From i_ndbm.U:

           This  variable  conditionally  defines  the "NDBM_H_USES_PROTOTYPES"
           symbol, which indicates that the gdbm-ndbm.h include file uses  real
           "ANSI"  C prototypes instead of K&R style function declarations. K&R
           style declarations are unsupported  in  C++,  so  the  include  file
           requires  special  handling  when  using  a  C++  compiler  and this
           variable     is      undefined.      Consult      the      different
           d_*ndbm_h_uses_prototypes  variables to get the same information for
           alternative ndbm.h include files.

       "d_gdbmndbm_h_uses_prototypes"
           From i_ndbm.U:

           This variable  conditionally  defines  the  "NDBM_H_USES_PROTOTYPES"
           symbol,  which indicates that the gdbm/ndbm.h include file uses real
           "ANSI" C prototypes instead of K&R style function declarations.  K&R
           style  declarations  are  unsupported  in  C++,  so the include file
           requires special  handling  when  using  a  C++  compiler  and  this
           variable      is      undefined.      Consult      the     different
           d_*ndbm_h_uses_prototypes variables to get the same information  for
           alternative ndbm.h include files.

       "d_getaddrinfo"
           From d_getaddrinfo.U:

           This  variable  conditionally  defines the "HAS_GETADDRINFO" symbol,
           which indicates to the C program that the getaddrinfo() function  is
           available.

       "d_getcwd"
           From d_getcwd.U:

           This  variable  conditionally defines the "HAS_GETCWD" symbol, which
           indicates to the C program that the getcwd() routine is available to
           get the current working directory.

       "d_getenv_preserves_other_thread"
           From d_getenv_thread.U:

           This        variable        conditionally        defines         the
           "GETENV_PRESERVES_OTHER_THREAD"  symbol,  which  indicates  to the C
           program that the getenv() system call does not zap the static buffer
           in a different thread.

       "d_getespwnam"
           From d_getespwnam.U:

           This variable conditionally defines "HAS_GETESPWNAM" if getespwnam()
           is available to retrieve enhanced (shadow) password entries by name.

       "d_getfsstat"
           From d_getfsstat.U:

           This variable  conditionally  defines  the  "HAS_GETFSSTAT"  symbol,
           which  indicates  to  the  C program that the getfsstat() routine is
           available.

       "d_getgrent"
           From d_getgrent.U:

           This variable conditionally defines the "HAS_GETGRENT" symbol, which
           indicates to the C program that the getgrent() routine is  available
           for sequential access of the group database.

       "d_getgrent_r"
           From d_getgrent_r.U:

           This  variable  conditionally  defines  the "HAS_GETGRENT_R" symbol,
           which indicates to the C program that the  getgrent_r()  routine  is
           available.

       "d_getgrgid_r"
           From d_getgrgid_r.U:

           This  variable  conditionally  defines  the "HAS_GETGRGID_R" symbol,
           which indicates to the C program that the  getgrgid_r()  routine  is
           available.

       "d_getgrnam_r"
           From d_getgrnam_r.U:

           This  variable  conditionally  defines  the "HAS_GETGRNAM_R" symbol,
           which indicates to the C program that the  getgrnam_r()  routine  is
           available.

       "d_getgrps"
           From d_getgrps.U:

           This  variable  conditionally  defines  the  "HAS_GETGROUPS" symbol,
           which indicates to the C program that  the  getgroups()  routine  is
           available to get the list of process groups.

       "d_gethbyaddr"
           From d_gethbyad.U:

           This  variable conditionally defines the "HAS_GETHOSTBYADDR" symbol,
           which indicates to the C program that the gethostbyaddr() routine is
           available to look up hosts by their "IP" addresses.

       "d_gethbyname"
           From d_gethbynm.U:

           This variable conditionally defines the "HAS_GETHOSTBYNAME"  symbol,
           which indicates to the C program that the gethostbyname() routine is
           available to look up host names in some data base or other.

       "d_gethent"
           From d_gethent.U:

           This variable conditionally defines "HAS_GETHOSTENT" if gethostent()
           is available to look up host names in some data base or another.

       "d_gethname"
           From d_gethname.U:

           This  variable  conditionally  defines the "HAS_GETHOSTNAME" symbol,
           which indicates to the C program that the gethostname() routine  may
           be used to derive the host name.

       "d_gethostbyaddr_r"
           From d_gethostbyaddr_r.U:

           This   variable   conditionally  defines  the  "HAS_GETHOSTBYADDR_R"
           symbol, which indicates to the C program that the  gethostbyaddr_r()
           routine is available.

       "d_gethostbyname_r"
           From d_gethostbyname_r.U:

           This   variable   conditionally  defines  the  "HAS_GETHOSTBYNAME_R"
           symbol, which indicates to the C program that the  gethostbyname_r()
           routine is available.

       "d_gethostent_r"
           From d_gethostent_r.U:

           This  variable  conditionally defines the "HAS_GETHOSTENT_R" symbol,
           which indicates to the C program that the gethostent_r() routine  is
           available.

       "d_gethostprotos"
           From d_gethostprotos.U:

           This variable conditionally defines the "HAS_GETHOST_PROTOS" symbol,
           which  indicates to the C program that <netdb.h> supplies prototypes
           for the various gethost*()  functions.   See  also  netdbtype.U  for
           probing for various netdb types.

       "d_getitimer"
           From d_getitimer.U:

           This  variable  conditionally  defines  the  "HAS_GETITIMER" symbol,
           which indicates to the C program that  the  getitimer()  routine  is
           available.

       "d_getlogin"
           From d_getlogin.U:

           This variable conditionally defines the "HAS_GETLOGIN" symbol, which
           indicates  to the C program that the getlogin() routine is available
           to get the login name.

       "d_getlogin_r"
           From d_getlogin_r.U:

           This variable conditionally  defines  the  "HAS_GETLOGIN_R"  symbol,
           which  indicates  to  the C program that the getlogin_r() routine is
           available.

       "d_getmnt"
           From d_getmnt.U:

           This variable conditionally defines the "HAS_GETMNT"  symbol,  which
           indicates to the C program that the getmnt() routine is available to
           retrieve one or more mount info blocks by filename.

       "d_getmntent"
           From d_getmntent.U:

           This  variable  conditionally  defines  the  "HAS_GETMNTENT" symbol,
           which indicates to the C program that  the  getmntent()  routine  is
           available to iterate through mounted files to get their mount info.

       "d_getnameinfo"
           From d_getnameinfo.U:

           This  variable  conditionally  defines the "HAS_GETNAMEINFO" symbol,
           which indicates to the C program that the getnameinfo() function  is
           available.

       "d_getnbyaddr"
           From d_getnbyad.U:

           This  variable  conditionally defines the "HAS_GETNETBYADDR" symbol,
           which indicates to the C program that the getnetbyaddr() routine  is
           available to look up networks by their "IP" addresses.

       "d_getnbyname"
           From d_getnbynm.U:

           This  variable  conditionally defines the "HAS_GETNETBYNAME" symbol,
           which indicates to the C program that the getnetbyname() routine  is
           available to look up networks by their names.

       "d_getnent"
           From d_getnent.U:

           This  variable  conditionally defines "HAS_GETNETENT" if getnetent()
           is available to look up network names in some data base or another.

       "d_getnetbyaddr_r"
           From d_getnetbyaddr_r.U:

           This variable conditionally defines the "HAS_GETNETBYADDR_R" symbol,
           which indicates to the C program that the  getnetbyaddr_r()  routine
           is available.

       "d_getnetbyname_r"
           From d_getnetbyname_r.U:

           This variable conditionally defines the "HAS_GETNETBYNAME_R" symbol,
           which  indicates  to the C program that the getnetbyname_r() routine
           is available.

       "d_getnetent_r"
           From d_getnetent_r.U:

           This variable conditionally defines  the  "HAS_GETNETENT_R"  symbol,
           which  indicates  to the C program that the getnetent_r() routine is
           available.

       "d_getnetprotos"
           From d_getnetprotos.U:

           This variable conditionally defines the "HAS_GETNET_PROTOS"  symbol,
           which  indicates to the C program that <netdb.h> supplies prototypes
           for the various  getnet*()  functions.   See  also  netdbtype.U  for
           probing for various netdb types.

       "d_getpagsz"
           From d_getpagsz.U:

           This    variable    conditionally   defines   "HAS_GETPAGESIZE"   if
           getpagesize() is available to get the system page size.

       "d_getpbyname"
           From d_getprotby.U:

           This variable conditionally defines the "HAS_GETPROTOBYNAME" symbol,
           which indicates to the C program that the  getprotobyname()  routine
           is available to look up protocols by their name.

       "d_getpbynumber"
           From d_getprotby.U:

           This   variable  conditionally  defines  the  "HAS_GETPROTOBYNUMBER"
           symbol, which indicates to the C program that the getprotobynumber()
           routine is available to look up protocols by their number.

       "d_getpent"
           From d_getpent.U:

           This   variable   conditionally   defines    "HAS_GETPROTOENT"    if
           getprotoent() is available to look up protocols in some data base or
           another.

       "d_getpgid"
           From d_getpgid.U:

           This  variable conditionally defines the "HAS_GETPGID" symbol, which
           indicates to  the  C  program  that  the  getpgid(pid)  function  is
           available to get the process group id.

       "d_getpgrp"
           From d_getpgrp.U:

           This  variable  conditionally  defines "HAS_GETPGRP" if getpgrp() is
           available to get the current process group.

       "d_getpgrp2"
           From d_getpgrp2.U:

           This variable conditionally defines the HAS_GETPGRP2  symbol,  which
           indicates  to  the  C  program  that  the getpgrp2() (as in DG/"UX")
           routine is available to get the current process group.

       "d_getppid"
           From d_getppid.U:

           This variable conditionally defines the "HAS_GETPPID" symbol,  which
           indicates  to  the C program that the getppid() routine is available
           to get the parent process "ID".

       "d_getprior"
           From d_getprior.U:

           This   variable   conditionally   defines    "HAS_GETPRIORITY"    if
           getpriority() is available to get a process's priority.

       "d_getprotobyname_r"
           From d_getprotobyname_r.U:

           This   variable  conditionally  defines  the  "HAS_GETPROTOBYNAME_R"
           symbol, which indicates to the C program that the getprotobyname_r()
           routine is available.

       "d_getprotobynumber_r"
           From d_getprotobynumber_r.U:

           This variable  conditionally  defines  the  "HAS_GETPROTOBYNUMBER_R"
           symbol,    which    indicates    to   the   C   program   that   the
           getprotobynumber_r() routine is available.

       "d_getprotoent_r"
           From d_getprotoent_r.U:

           This variable conditionally defines the "HAS_GETPROTOENT_R"  symbol,
           which indicates to the C program that the getprotoent_r() routine is
           available.

       "d_getprotoprotos"
           From d_getprotoprotos.U:

           This   variable   conditionally  defines  the  "HAS_GETPROTO_PROTOS"
           symbol, which indicates to the C  program  that  <netdb.h>  supplies
           prototypes   for   the  various  getproto*()  functions.   See  also
           netdbtype.U for probing for various netdb types.

       "d_getprpwnam"
           From d_getprpwnam.U:

           This variable conditionally defines "HAS_GETPRPWNAM" if getprpwnam()
           is available to retrieve  protected  (shadow)  password  entries  by
           name.

       "d_getpwent"
           From d_getpwent.U:

           This variable conditionally defines the "HAS_GETPWENT" symbol, which
           indicates  to the C program that the getpwent() routine is available
           for sequential access of the passwd database.

       "d_getpwent_r"
           From d_getpwent_r.U:

           This variable conditionally  defines  the  "HAS_GETPWENT_R"  symbol,
           which  indicates  to  the C program that the getpwent_r() routine is
           available.

       "d_getpwnam_r"
           From d_getpwnam_r.U:

           This variable conditionally  defines  the  "HAS_GETPWNAM_R"  symbol,
           which  indicates  to  the C program that the getpwnam_r() routine is
           available.

       "d_getpwuid_r"
           From d_getpwuid_r.U:

           This variable conditionally  defines  the  "HAS_GETPWUID_R"  symbol,
           which  indicates  to  the C program that the getpwuid_r() routine is
           available.

       "d_getsbyname"
           From d_getsrvby.U:

           This variable conditionally defines the "HAS_GETSERVBYNAME"  symbol,
           which indicates to the C program that the getservbyname() routine is
           available to look up services by their name.

       "d_getsbyport"
           From d_getsrvby.U:

           This  variable conditionally defines the "HAS_GETSERVBYPORT" symbol,
           which indicates to the C program that the getservbyport() routine is
           available to look up services by their port.

       "d_getsent"
           From d_getsent.U:

           This variable conditionally defines "HAS_GETSERVENT" if getservent()
           is available to look up  network  services  in  some  data  base  or
           another.

       "d_getservbyname_r"
           From d_getservbyname_r.U:

           This   variable   conditionally  defines  the  "HAS_GETSERVBYNAME_R"
           symbol, which indicates to the C program that the  getservbyname_r()
           routine is available.

       "d_getservbyport_r"
           From d_getservbyport_r.U:

           This   variable   conditionally  defines  the  "HAS_GETSERVBYPORT_R"
           symbol, which indicates to the C program that the  getservbyport_r()
           routine is available.

       "d_getservent_r"
           From d_getservent_r.U:

           This  variable  conditionally defines the "HAS_GETSERVENT_R" symbol,
           which indicates to the C program that the getservent_r() routine  is
           available.

       "d_getservprotos"
           From d_getservprotos.U:

           This variable conditionally defines the "HAS_GETSERV_PROTOS" symbol,
           which  indicates to the C program that <netdb.h> supplies prototypes
           for the various getserv*()  functions.   See  also  netdbtype.U  for
           probing for various netdb types.

       "d_getspnam"
           From d_getspnam.U:

           This  variable conditionally defines "HAS_GETSPNAM" if getspnam() is
           available to retrieve SysV shadow password entries by name.

       "d_getspnam_r"
           From d_getspnam_r.U:

           This variable conditionally  defines  the  "HAS_GETSPNAM_R"  symbol,
           which  indicates  to  the C program that the getspnam_r() routine is
           available.

       "d_gettimeod"
           From d_ftime.U:

           This variable conditionally defines the  "HAS_GETTIMEOFDAY"  symbol,
           which  indicates  that  the  gettimeofday()  system  call exists (to
           obtain a sub-second accuracy clock).  You  should  probably  include
           <sys/resource.h>.

       "d_gmtime64"
           From d_timefuncs64.U:

           This  variable  conditionally defines the HAS_GMTIME64 symbol, which
           indicates  to  the  C  program  that  the  gmtime64  ()  routine  is
           available.

       "d_gmtime_r"
           From d_gmtime_r.U:

           This variable conditionally defines the "HAS_GMTIME_R" symbol, which
           indicates to the C program that the gmtime_r() routine is available.

       "d_gnulibc"
           From d_gnulibc.U:

           Defined if we're dealing with the "GNU" C Library.

       "d_grpasswd"
           From i_grp.U:

           This variable conditionally defines "GRPASSWD", which indicates that
           struct group in <grp.h> contains gr_passwd.

       "d_has_C_UTF8"
           From d_setlocale.U:

           This  variable  is  set  to  either  "true"  or "false" depending on
           whether the compilation system supports the C.UTF-8 locale.

       "d_hasmntopt"
           From d_hasmntopt.U:

           This variable  conditionally  defines  the  "HAS_HASMNTOPT"  symbol,
           which  indicates  to  the  C program that the hasmntopt() routine is
           available to query the mount options of file systems.

       "d_htonl"
           From d_htonl.U:

           This variable conditionally defines "HAS_HTONL" if htonl()  and  its
           friends are available to do network order byte swapping.

       "d_hypot"
           From d_hypot.U:

           This   variable   conditionally  defines  "HAS_HYPOT"  if  hypot  is
           available for numerically stable hypotenuse function.

       "d_ilogb"
           From d_ilogb.U:

           This variable conditionally defines the  "HAS_ILOGB"  symbol,  which
           indicates to the C program that the ilogb() routine is available for
           extracting the exponent of double x as a signed integer.

       "d_ilogbl"
           From d_ilogbl.U:

           This  variable  conditionally defines the "HAS_ILOGBL" symbol, which
           indicates to the C program that the ilogbl()  routine  is  available
           for  extracting  the  exponent of long double x as a signed integer.
           If scalbnl is also present we can emulate frexpl.

       "d_inc_version_list"
           From inc_version_list.U:

           This variable conditionally defines "PERL_INC_VERSION_LIST".  It  is
           set to undef when "PERL_INC_VERSION_LIST" is empty.

       "d_inetaton"
           From d_inetaton.U:

           This  variable  conditionally  defines  the  "HAS_INET_ATON" symbol,
           which indicates to the C program that the  inet_aton()  function  is
           available to parse "IP" address "dotted-quad" strings.

       "d_inetntop"
           From d_inetntop.U:

           This variable conditionally defines the "HAS_INETNTOP" symbol, which
           indicates  to  the  C  program  that  the  inet_ntop()  function  is
           available.

       "d_inetpton"
           From d_inetpton.U:

           This variable conditionally defines the "HAS_INETPTON" symbol, which
           indicates  to  the  C  program  that  the  inet_pton()  function  is
           available.

       "d_int64_t"
           From d_int64_t.U:

           This symbol will be defined if the C compiler supports int64_t.

       "d_ip_mreq"
           From d_socket.U:

           This  variable conditionally defines the "HAS_IP_MREQ" symbol, which
           indicates the availability of a struct ip_mreq.

       "d_ip_mreq_source"
           From d_socket.U:

           This variable conditionally defines the "HAS_IP_MREQ_SOURCE" symbol,
           which indicates the availability of a struct ip_mreq_source.

       "d_ipv6_mreq"
           From d_socket.U:

           This variable conditionally defines the HAS_IPV6_MREQ symbol,  which
           indicates the availability of a struct ipv6_mreq.

       "d_ipv6_mreq_source"
           From d_socket.U:

           This variable conditionally defines the HAS_IPV6_MREQ_SOURCE symbol,
           which indicates the availability of a struct ipv6_mreq_source.

       "d_isascii"
           From d_isascii.U:

           This  variable  conditionally  defines  the  "HAS_ISASCII" constant,
           which indicates to the C program that isascii() is available.

       "d_isblank"
           From d_isblank.U:

           This variable  conditionally  defines  the  "HAS_ISBLANK"  constant,
           which indicates to the C program that isblank() is available.

       "d_isfinite"
           From d_isfinite.U:

           This variable conditionally defines the "HAS_ISFINITE" symbol, which
           indicates to the C program that the isfinite() routine is available.

       "d_isfinitel"
           From d_isfinitel.U:

           This  variable  conditionally  defines  the  "HAS_ISFINITEL" symbol,
           which indicates to the C program that  the  isfinitel()  routine  is
           available.

       "d_isinf"
           From d_isinf.U:

           This  variable  conditionally  defines the "HAS_ISINF" symbol, which
           indicates to the C program that the isinf() routine is available.

       "d_isinfl"
           From d_isinfl.U:

           This variable conditionally defines the "HAS_ISINFL"  symbol,  which
           indicates to the C program that the isinfl() routine is available.

       "d_isless"
           From d_isless.U:

           This  variable  conditionally defines the "HAS_ISLESS" symbol, which
           indicates to the C program that the isless() routine is available.

       "d_isnan"
           From d_isnan.U:

           This variable conditionally defines the  "HAS_ISNAN"  symbol,  which
           indicates to the C program that the isnan() routine is available.

       "d_isnanl"
           From d_isnanl.U:

           This  variable  conditionally defines the "HAS_ISNANL" symbol, which
           indicates to the C program that the isnanl() routine is available.

       "d_isnormal"
           From d_isnormal.U:

           This variable conditionally defines the "HAS_ISNORMAL" symbol, which
           indicates to the C program that the isnormal() routine is available.

       "d_j0"
           From d_j0.U:

           This  variable  conditionally  defines  the  HAS_J0  symbol,   which
           indicates to the C program that the j0() routine is available.

       "d_j0l"
           From d_j0.U:

           This  variable  conditionally  defines  the  HAS_J0L  symbol,  which
           indicates to the C program that the j0l() routine is available.

       "d_killpg"
           From d_killpg.U:

           This variable conditionally defines the "HAS_KILLPG"  symbol,  which
           indicates to the C program that the killpg() routine is available to
           kill process groups.

       "d_lc_monetary_2008"
           From d_lc_monetary_2008.U:

           This variable conditionally defines HAS_LC_MONETARY_2008 if libc has
           the international currency locale rules from "POSIX" 1003.1-2008.

       "d_lchown"
           From d_lchown.U:

           This  variable  conditionally defines the "HAS_LCHOWN" symbol, which
           indicates to the C program that the lchown() routine is available to
           operate on a symbolic link (instead of following the link).

       "d_ldbl_dig"
           From d_ldbl_dig.U:

           This variable conditionally  defines  d_ldbl_dig  if  this  system's
           header  files provide "LDBL_DIG", which is the number of significant
           digits in a long double precision number.

       "d_ldexpl"
           From d_longdbl.U:

           This variable conditionally defines the "HAS_LDEXPL"  symbol,  which
           indicates to the C program that the ldexpl() routine is available.

       "d_lgamma"
           From d_lgamma.U:

           This  variable  conditionally defines the "HAS_LGAMMA" symbol, which
           indicates to the C program that the lgamma()  routine  is  available
           for the log gamma function.  See also d_tgamma and d_lgamma_r.

       "d_lgamma_r"
           From d_lgamma_r.U:

           This variable conditionally defines the "HAS_LGAMMA_R" symbol, which
           indicates  to the C program that the lgamma_r() routine is available
           for the  log  gamma  function,  without  using  the  global  signgam
           variable.

       "d_libm_lib_version"
           From d_libm_lib_version.U:

           This  variable  conditionally defines the "LIBM_LIB_VERSION" symbol,
           which indicates to the C program that math.h defines  "_LIB_VERSION"
           being available in libm

       "d_libname_unique"
           From so.U:

           This  variable  is  defined  if  the target system insists on unique
           basenames for shared  library  files.  This  is  currently  true  on
           Android, false everywhere else we know of.  Defaults to "undef".

       "d_link"
           From d_link.U:

           This   variable   conditionally  defines  "HAS_LINK"  if  link()  is
           available to create hard links.

       "d_linkat"
           From d_fsat.U:

           This variable conditionally defines the "HAS_LINKAT"  symbol,  which
           indicates the "POSIX" linkat() function is available.

       "d_llrint"
           From d_llrint.U:

           This  variable  conditionally defines the "HAS_LLRINT" symbol, which
           indicates to the C program that the llrint() routine is available to
           return the long long value closest to a  double  (according  to  the
           current rounding mode).

       "d_llrintl"
           From d_llrintl.U:

           This  variable conditionally defines the "HAS_LLRINTL" symbol, which
           indicates to the C program that the llrintl() routine  is  available
           to return the long long value closest to a long double (according to
           the current rounding mode).

       "d_llround"
           From d_llround.U:

           This  variable conditionally defines the "HAS_LLROUND" symbol, which
           indicates to the C program that the llround() routine  is  available
           to return the long long value nearest to x.

       "d_llroundl"
           From d_llroundl.U:

           This variable conditionally defines the "HAS_LLROUNDL" symbol, which
           indicates  to the C program that the llroundl() routine is available
           to return the long long value nearest to x away from zero.

       "d_localeconv_l"
           From d_localeconv_l.U:

           This variable conditionally defines the  "HAS_LOCALECONV_L"  symbol,
           which  indicates to the C program that the localeconv_l() routine is
           available.

       "d_localtime64"
           From d_timefuncs64.U:

           This variable  conditionally  defines  the  HAS_LOCALTIME64  symbol,
           which  indicates to the C program that the localtime64 () routine is
           available.

       "d_localtime_r"
           From d_localtime_r.U:

           This variable conditionally defines  the  "HAS_LOCALTIME_R"  symbol,
           which  indicates  to the C program that the localtime_r() routine is
           available.

       "d_localtime_r_needs_tzset"
           From d_localtime_r.U:

           This variable conditionally  defines  the  "LOCALTIME_R_NEEDS_TZSET"
           symbol, which makes us call tzset before localtime_r()

       "d_locconv"
           From d_locconv.U:

           This variable conditionally defines "HAS_LOCALECONV" if localeconv()
           is available for numeric and monetary formatting conventions.

       "d_lockf"
           From d_lockf.U:

           This  variable  conditionally  defines  "HAS_LOCKF"  if  lockf()  is
           available to do file locking.

       "d_log1p"
           From d_log1p.U:

           This variable conditionally  defines  the  HAS_LOG1P  symbol,  which
           indicates  to the C program that the logp1() routine is available to
           compute log(1 + x) for values of x close to zero.

       "d_log2"
           From d_log2.U:

           This variable  conditionally  defines  the  HAS_LOG2  symbol,  which
           indicates  to  the C program that the log2() routine is available to
           compute log base two.

       "d_logb"
           From d_logb.U:

           This variable conditionally defines  the  "HAS_LOGB"  symbol,  which
           indicates  to  the C program that the logb() routine is available to
           extract the exponent of x.

       "d_long_double_style_ieee"
           From d_longdbl.U:

           This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE" if  the
           long   double   is  any  of  the  "IEEE"  754  style  long  doubles:
           "LONG_DOUBLE_STYLE_IEEE_STD",     "LONG_DOUBLE_STYLE_IEEE_EXTENDED",
           "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE".

       "d_long_double_style_ieee_doubledouble"
           From d_longdbl.U:

           This            variable            conditionally            defines
           "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE" if  the  long  double  is  the
           128-bit "IEEE" 754 double-double.

       "d_long_double_style_ieee_extended"
           From d_longdbl.U:

           This            variable            conditionally            defines
           "LONG_DOUBLE_STYLE_IEEE_EXTENDED" if the long double is  the  80-bit
           "IEEE"  754  extended  precision.   Note that despite the "extended"
           this is less than the "std", since  this  is  an  extension  of  the
           double precision.

       "d_long_double_style_ieee_std"
           From d_longdbl.U:

           This  variable conditionally defines "LONG_DOUBLE_STYLE_IEEE_STD" if
           the long double is the 128-bit "IEEE" 754.

       "d_long_double_style_vax"
           From d_longdbl.U:

           This variable conditionally defines "LONG_DOUBLE_STYLE_VAX"  if  the
           long double is the 128-bit "VAX" format H.

       "d_longdbl"
           From d_longdbl.U:

           This  variable  conditionally  defines "HAS_LONG_DOUBLE" if the long
           double type is supported.

       "d_longlong"
           From d_longlong.U:

           This variable conditionally defines "HAS_LONG_LONG" if the long long
           type is supported.

       "d_lrint"
           From d_lrint.U:

           This variable conditionally defines the  "HAS_LRINT"  symbol,  which
           indicates  to the C program that the lrint() routine is available to
           return the integral value closest to  a  double  (according  to  the
           current rounding mode).

       "d_lrintl"
           From d_lrintl.U:

           This  variable  conditionally defines the "HAS_LRINTL" symbol, which
           indicates to the C program that the lrintl() routine is available to
           return the integral value closest to a long double (according to the
           current rounding mode).

       "d_lround"
           From d_lround.U:

           This variable conditionally defines the "HAS_LROUND"  symbol,  which
           indicates to the C program that the lround() routine is available to
           return the integral value nearest to x.

       "d_lroundl"
           From d_lroundl.U:

           This  variable conditionally defines the "HAS_LROUNDL" symbol, which
           indicates to the C program that the lroundl() routine  is  available
           to return the integral value nearest to x away from zero.

       "d_lseekproto"
           From d_lseekproto.U:

           This  variable  conditionally  defines the "HAS_LSEEK_PROTO" symbol,
           which indicates  to  the  C  program  that  the  system  provides  a
           prototype  for  the  lseek()  function.   Otherwise, it is up to the
           program to supply one.

       "d_lstat"
           From d_lstat.U:

           This  variable  conditionally  defines  "HAS_LSTAT"  if  lstat()  is
           available to do file stats on symbolic links.

       "d_madvise"
           From d_madvise.U:

           This  variable  conditionally  defines "HAS_MADVISE" if madvise() is
           available to map a file into memory.

       "d_malloc_good_size"
           From d_malloc_size.U:

           This symbol, if defined, indicates that the malloc_good_size routine
           is available for use.

       "d_malloc_size"
           From d_malloc_size.U:

           This symbol, if defined, indicates that the malloc_size  routine  is
           available for use.

       "d_malloc_usable_size"
           From d_malloc_size.U:

           This  symbol,  if  defined,  indicates  that  the malloc_usable_size
           routine is available for use.

       "d_mblen"
           From d_mblen.U:

           This variable conditionally defines the  "HAS_MBLEN"  symbol,  which
           indicates  to the C program that the mblen() routine is available to
           find the number of bytes in a multibyte character.

       "d_mbrlen"
           From d_mbrlen.U:

           This variable conditionally defines the "HAS_MBRLEN" symbol  if  the
           mbrlen() routine is available to be used to get the length of multi-
           byte character strings.

       "d_mbrtowc"
           From d_mbrtowc.U:

           This  variable conditionally defines the "HAS_MBRTOWC" symbol if the
           mbrtowc() routine is available to be used to  convert  a  multi-byte
           character into a wide character.

       "d_mbstowcs"
           From d_mbstowcs.U:

           This variable conditionally defines the "HAS_MBSTOWCS" symbol, which
           indicates  to the C program that the mbstowcs() routine is available
           to convert a multibyte string into a wide character string.

       "d_mbtowc"
           From d_mbtowc.U:

           This variable conditionally defines the "HAS_MBTOWC"  symbol,  which
           indicates to the C program that the mbtowc() routine is available to
           convert multibyte to a wide character.

       "d_memmem"
           From d_memmem.U:

           This  variable  conditionally defines the "HAS_MEMMEM" symbol, which
           indicates to the C program that the memmem() routine is available to
           return a pointer to the start of the first occurrence of a substring
           in a memory area (or "NULL" if not found).

       "d_memrchr"
           From d_memrchr.U:

           This variable conditionally defines the "HAS_MEMRCHR" symbol,  which
           indicates  to  the C program that the memrchr() routine is available
           to return a pointer to the last occurrence of a  byte  in  a  memory
           area (or "NULL" if not found).

       "d_mkdir"
           From d_mkdir.U:

           This  variable  conditionally  defines the "HAS_MKDIR" symbol, which
           indicates to the C program that the mkdir() routine is available  to
           create directories..

       "d_mkdtemp"
           From d_mkdtemp.U:

           This  variable conditionally defines the "HAS_MKDTEMP" symbol, which
           indicates to the C program that the mkdtemp() routine  is  available
           to exclusively create a uniquely named temporary directory.

       "d_mkfifo"
           From d_mkfifo.U:

           This  variable  conditionally defines the "HAS_MKFIFO" symbol, which
           indicates to the C program that the mkfifo() routine is available.

       "d_mkostemp"
           From d_mkostemp.U:

           This variable conditionally defines "HAS_MKOSTEMP" if mkostemp()  is
           available  to  exclusively  create and open a uniquely named (with a
           suffix) temporary file.

       "d_mkstemp"
           From d_mkstemp.U:

           This variable conditionally defines the "HAS_MKSTEMP" symbol,  which
           indicates  to  the C program that the mkstemp() routine is available
           to exclusively create and open a uniquely named temporary file.

       "d_mkstemps"
           From d_mkstemps.U:

           This variable conditionally defines the "HAS_MKSTEMPS" symbol, which
           indicates to the C program that the mkstemps() routine is  available
           to  exclusively  create  and  open  a uniquely named (with a suffix)
           temporary file.

       "d_mktime"
           From d_mktime.U:

           This variable conditionally defines the "HAS_MKTIME"  symbol,  which
           indicates to the C program that the mktime() routine is available.

       "d_mktime64"
           From d_timefuncs64.U:

           This  variable  conditionally defines the HAS_MKTIME64 symbol, which
           indicates  to  the  C  program  that  the  mktime64  ()  routine  is
           available.

       "d_mmap"
           From d_mmap.U:

           This   variable   conditionally  defines  "HAS_MMAP"  if  mmap()  is
           available to map a file into memory.

       "d_modfl"
           From d_modfl.U:

           This variable conditionally defines the  "HAS_MODFL"  symbol,  which
           indicates to the C program that the modfl() routine is available.

       "d_modflproto"
           From d_modfl.U:

           This  symbol,  if  defined,  indicates  that  the  system provides a
           prototype for the modfl() function.  Otherwise,  it  is  up  to  the
           program to supply one.  C99 says it should be long double modfl(long
           double, long double *);

       "d_mprotect"
           From d_mprotect.U:

           This  variable conditionally defines "HAS_MPROTECT" if mprotect() is
           available to modify the access protection of a memory mapped file.

       "d_msg"
           From d_msg.U:

           This variable conditionally  defines  the  "HAS_MSG"  symbol,  which
           indicates that the entire msg*(2) library is present.

       "d_msg_ctrunc"
           From d_socket.U:

           This  variable  conditionally  defines  the "HAS_MSG_CTRUNC" symbol,
           which indicates that the "MSG_CTRUNC" is available.  #ifdef  is  not
           enough because it may be an enum, glibc has been known to do this.

       "d_msg_dontroute"
           From d_socket.U:

           This  variable conditionally defines the "HAS_MSG_DONTROUTE" symbol,
           which indicates that the "MSG_DONTROUTE" is  available.   #ifdef  is
           not  enough  because  it  may be an enum, glibc has been known to do
           this.

       "d_msg_oob"
           From d_socket.U:

           This variable conditionally defines the "HAS_MSG_OOB" symbol,  which
           indicates  that  the  "MSG_OOB"  is available.  #ifdef is not enough
           because it may be an enum, glibc has been known to do this.

       "d_msg_peek"
           From d_socket.U:

           This variable conditionally defines the "HAS_MSG_PEEK" symbol, which
           indicates that the "MSG_PEEK" is available.  #ifdef  is  not  enough
           because it may be an enum, glibc has been known to do this.

       "d_msg_proxy"
           From d_socket.U:

           This  variable  conditionally  defines  the  "HAS_MSG_PROXY" symbol,
           which indicates that the "MSG_PROXY" is available.   #ifdef  is  not
           enough because it may be an enum, glibc has been known to do this.

       "d_msgctl"
           From d_msgctl.U:

           This  variable  conditionally defines the "HAS_MSGCTL" symbol, which
           indicates to the C program that the msgctl() routine is available.

       "d_msgget"
           From d_msgget.U:

           This variable conditionally defines the "HAS_MSGGET"  symbol,  which
           indicates to the C program that the msgget() routine is available.

       "d_msghdr_s"
           From d_msghdr_s.U:

           This  variable conditionally defines the "HAS_STRUCT_MSGHDR" symbol,
           which indicates that the struct msghdr is supported.

       "d_msgrcv"
           From d_msgrcv.U:

           This variable conditionally defines the "HAS_MSGRCV"  symbol,  which
           indicates to the C program that the msgrcv() routine is available.

       "d_msgsnd"
           From d_msgsnd.U:

           This  variable  conditionally defines the "HAS_MSGSND" symbol, which
           indicates to the C program that the msgsnd() routine is available.

       "d_msync"
           From d_msync.U:

           This  variable  conditionally  defines  "HAS_MSYNC"  if  msync()  is
           available to synchronize a mapped file.

       "d_munmap"
           From d_munmap.U:

           This  variable  conditionally  defines  "HAS_MUNMAP"  if munmap() is
           available to unmap a region mapped by mmap().

       "d_mymalloc"
           From mallocsrc.U:

           This variable conditionally defines "MYMALLOC" in case  other  parts
           of  the  source  want  to take special action if "MYMALLOC" is used.
           This may include different sorts of profiling or error detection.

       "d_nan"
           From d_nan.U:

           This variable conditionally defines "HAS_NAN" if nan() is  available
           to generate NaN.

       "d_nanosleep"
           From d_nanosleep.U:

           This  variable  conditionally defines "HAS_NANOSLEEP" if nanosleep()
           is available to sleep with 1E-9 sec accuracy.

       "d_ndbm"
           From i_ndbm.U:

           This variable conditionally defines  the  "HAS_NDBM"  symbol,  which
           indicates  that both the ndbm.h include file and an appropriate ndbm
           library exist.  Consult the different i_*ndbm variables to find  out
           the  actual  include  location.   Sometimes, a system has the header
           file but not the library.  This variable will only  be  set  if  the
           system has both.

       "d_ndbm_h_uses_prototypes"
           From i_ndbm.U:

           This  variable  conditionally  defines  the "NDBM_H_USES_PROTOTYPES"
           symbol, which indicates that  the  ndbm.h  include  file  uses  real
           "ANSI"  C prototypes instead of K&R style function declarations. K&R
           style declarations are unsupported  in  C++,  so  the  include  file
           requires  special  handling  when  using  a  C++  compiler  and this
           variable     is      undefined.      Consult      the      different
           d_*ndbm_h_uses_prototypes  variables to get the same information for
           alternative ndbm.h include files.

       "d_nearbyint"
           From d_nearbyint.U:

           This variable conditionally defines "HAS_NEARBYINT"  if  nearbyint()
           is  available  to return the integral value closest to (according to
           the current rounding mode) to x.

       "d_newlocale"
           From d_newlocale.U:

           This variable  conditionally  defines  the  "HAS_NEWLOCALE"  symbol,
           which  indicates  to  the  C program that the newlocale() routine is
           available to return a new locale object or modify an existing locale
           object.

       "d_nextafter"
           From d_nextafter.U:

           This variable conditionally defines "HAS_NEXTAFTER"  if  nextafter()
           is  available to return the next machine representable double from x
           in direction y.

       "d_nexttoward"
           From d_nexttoward.U:

           This variable conditionally defines "HAS_NEXTTOWARD" if nexttoward()
           is available to return the next machine  representable  long  double
           from x in direction y.

       "d_nice"
           From d_nice.U:

           This  variable  conditionally  defines  the "HAS_NICE" symbol, which
           indicates to the C program that the nice() routine is available.

       "d_nl_langinfo"
           From d_nl_langinfo.U:

           This variable conditionally defines  the  "HAS_NL_LANGINFO"  symbol,
           which  indicates  to the C program that the nl_langinfo() routine is
           available.

       "d_nl_langinfo_l"
           From d_nl_langinfo.U:

           This variable conditionally defines the "HAS_NL_LANGINFO_L"  symbol,
           which indicates to the C program that the nl_langinfo_l() routine is
           available.

       "d_non_int_bitfields"
           From d_bitfield.U:

           This  variable  conditionally  defines "HAS_NON_INT_BITFIELDS" which
           indicates that the C compiler accepts struct bitfields of sizes that
           aren't "int" or "unsigned int"

       "d_nv_preserves_uv"
           From perlxv.U:

           This variable indicates  whether  a  variable  of  type  nvtype  can
           preserve all the bits a variable of type uvtype.

       "d_nv_zero_is_allbits_zero"
           From perlxv.U:

           This variable indicates whether a variable of type nvtype stores 0.0
           in memory as all bits zero.

       "d_off64_t"
           From d_off64_t.U:

           This symbol will be defined if the C compiler supports off64_t.

       "d_old_pthread_create_joinable"
           From d_pthrattrj.U:

           This  variable conditionally defines pthread_create_joinable.  undef
           if pthread.h defines "PTHREAD_CREATE_JOINABLE".

       "d_oldpthreads"
           From usethreads.U:

           This variable conditionally defines the  "OLD_PTHREADS_API"  symbol,
           and indicates that Perl should be built to use the old draft "POSIX"
           threads "API".  This is only potentially meaningful if usethreads is
           set.

       "d_oldsock"
           From d_socket.U:

           This  variable  conditionally  defines the "OLDSOCKET" symbol, which
           indicates that the "BSD" socket interface is based on 4.1c  and  not
           4.2.

       "d_open3"
           From d_open3.U:

           This variable conditionally defines the HAS_OPEN3 manifest constant,
           which  indicates to the C program that the 3 argument version of the
           open(2) function is available.

       "d_openat"
           From d_fsat.U:

           This variable conditionally defines the "HAS_OPENAT"  symbol,  which
           indicates the "POSIX" openat() function is available.

       "d_pathconf"
           From d_pathconf.U:

           This variable conditionally defines the "HAS_PATHCONF" symbol, which
           indicates  to the C program that the pathconf() routine is available
           to determine file-system related limits and options associated  with
           a given filename.

       "d_pause"
           From d_pause.U:

           This  variable  conditionally  defines the "HAS_PAUSE" symbol, which
           indicates to the C program that the pause() routine is available  to
           suspend a process until a signal is received.

       "d_perl_lc_all_category_positions_init"
           From disparate_lc_all.U:

           This       symbol,       if       defined,       indicates      that
           $lc_all_category_positions_init is valid

       "d_perl_lc_all_separator"
           From disparate_lc_all.U:

           This symbol, if defined, indicates  that  $perl_lc_all_separator  is
           valid

       "d_perl_lc_all_uses_name_value_pairs"
           From disparate_lc_all.U:

           This  symbol,  if  defined,  indicates  that  the string returned by
           setlocale("LC_ALL", "NULL") uses  "name=value;"  pairs  to  indicate
           what  each category's locale is when they aren't all set to the same
           locale.  When not defined, the platform uses positional notation.

       "d_perl_otherlibdirs"
           From otherlibdirs.U:

           This  variable  conditionally  defines  "PERL_OTHERLIBDIRS",   which
           contains  a  colon-separated  set  of  paths  for the perl binary to
           include in @"INC".  See also otherlibdirs.

       "d_phostname"
           From d_gethname.U:

           This variable  conditionally  defines  the  "HAS_PHOSTNAME"  symbol,
           which  contains the shell command which, when fed to popen(), may be
           used to derive the host name.

       "d_pipe"
           From d_pipe.U:

           This variable conditionally defines  the  "HAS_PIPE"  symbol,  which
           indicates  to  the C program that the pipe() routine is available to
           create an inter-process channel.

       "d_pipe2"
           From d_pipe2.U:

           This variable conditionally  defines  the  HAS_PIPE2  symbol,  which
           indicates  to the C program that the pipe2() routine is available to
           create an inter-process channel.

       "d_poll"
           From d_poll.U:

           This variable conditionally defines  the  "HAS_POLL"  symbol,  which
           indicates  to  the C program that the poll() routine is available to
           poll active file descriptors.

       "d_portable"
           From d_portable.U:

           This variable conditionally defines  the  "PORTABLE"  symbol,  which
           indicates  to  the  C  program  that it should not assume that it is
           running on the machine it was compiled on.

       "d_prctl"
           From d_prctl.U:

           This variable conditionally defines the  "HAS_PRCTL"  symbol,  which
           indicates  to  the  C program that the prctl() routine is available.
           Note that there are at least two prctl  variants:  Linux  and  Irix.
           While they are somewhat similar, they are incompatible.

       "d_prctl_set_name"
           From d_prctl.U:

           This variable conditionally defines the "HAS_PRCTL_SET_NAME" symbol,
           which  indicates  to the C program that the prctl() routine supports
           the "PR_SET_NAME" option.

       "d_printf_format_null"
           From d_attribut.U:

           This variable conditionally defines  "PRINTF_FORMAT_NULL_OK",  which
           indicates the C compiler allows printf-like formats to be null.

       "d_procselfexe"
           From d_procselfexe.U:

           Defined  if  $procselfexe is symlink to the absolute pathname of the
           executing program.

       "d_pseudofork"
           From d_vfork.U:

           This variable conditionally  defines  the  "HAS_PSEUDOFORK"  symbol,
           which indicates that an emulation of the fork routine is available.

       "d_pthread_atfork"
           From d_pthread_atfork.U:

           This variable conditionally defines the "HAS_PTHREAD_ATFORK" symbol,
           which  indicates  to the C program that the pthread_atfork() routine
           is available.

       "d_pthread_attr_setscope"
           From d_pthread_attr_ss.U:

           This variable conditionally defines  "HAS_PTHREAD_ATTR_SETSCOPE"  if
           pthread_attr_setscope()  is  available  to  set the contention scope
           attribute of a thread attribute object.

       "d_pthread_yield"
           From d_pthread_y.U:

           This variable conditionally defines the  "HAS_PTHREAD_YIELD"  symbol
           if  the pthread_yield routine is available to yield the execution of
           the current thread.

       "d_ptrdiff_t"
           From d_ptrdiff_t.U:

           This symbol will be defined if the C compiler supports ptrdiff_t.

       "d_pwage"
           From i_pwd.U:

           This variable conditionally defines "PWAGE",  which  indicates  that
           struct passwd contains pw_age.

       "d_pwchange"
           From i_pwd.U:

           This variable conditionally defines "PWCHANGE", which indicates that
           struct passwd contains pw_change.

       "d_pwclass"
           From i_pwd.U:

           This  variable conditionally defines "PWCLASS", which indicates that
           struct passwd contains pw_class.

       "d_pwcomment"
           From i_pwd.U:

           This variable conditionally  defines  "PWCOMMENT",  which  indicates
           that struct passwd contains pw_comment.

       "d_pwexpire"
           From i_pwd.U:

           This variable conditionally defines "PWEXPIRE", which indicates that
           struct passwd contains pw_expire.

       "d_pwgecos"
           From i_pwd.U:

           This  variable conditionally defines "PWGECOS", which indicates that
           struct passwd contains pw_gecos.

       "d_pwpasswd"
           From i_pwd.U:

           This variable conditionally defines "PWPASSWD", which indicates that
           struct passwd contains pw_passwd.

       "d_pwquota"
           From i_pwd.U:

           This variable conditionally defines "PWQUOTA", which indicates  that
           struct passwd contains pw_quota.

       "d_qgcvt"
           From d_qgcvt.U:

           This  variable  conditionally  defines the "HAS_QGCVT" symbol, which
           indicates to the C program that the qgcvt() routine is available.

       "d_quad"
           From quadtype.U:

           This variable, if defined, tells that there's a 64-bit integer type,
           quadtype.

       "d_querylocale"
           From d_newlocale.U:

           This variable conditionally defines  the  "HAS_QUERYLOCALE"  symbol,
           which  indicates  to the C program that the querylocale() routine is
           available to return the name of the locale for a category mask.

       "d_random_r"
           From d_random_r.U:

           This variable conditionally defines the "HAS_RANDOM_R" symbol, which
           indicates to the C program that the random_r() routine is available.

       "d_re_comp"
           From d_regcmp.U:

           This variable conditionally defines the "HAS_RECOMP"  symbol,  which
           indicates  to  the C program that the re_comp() routine is available
           for regular pattern matching (usually on "BSD"). If so, it is likely
           that re_exec() exists.

       "d_readdir"
           From d_readdir.U:

           This variable conditionally defines "HAS_READDIR"  if  readdir()  is
           available to read directory entries.

       "d_readdir64_r"
           From d_readdir64_r.U:

           This  variable  conditionally  defines  the  HAS_READDIR64_R symbol,
           which indicates to the C program that the readdir64_r()  routine  is
           available.

       "d_readdir_r"
           From d_readdir_r.U:

           This  variable  conditionally  defines  the  "HAS_READDIR_R" symbol,
           which indicates to the C program that  the  readdir_r()  routine  is
           available.

       "d_readlink"
           From d_readlink.U:

           This variable conditionally defines the "HAS_READLINK" symbol, which
           indicates  to the C program that the readlink() routine is available
           to read the value of a symbolic link.

       "d_readv"
           From d_readv.U:

           This variable conditionally defines the  "HAS_READV"  symbol,  which
           indicates to the C program that the readv() routine is available.

       "d_recvmsg"
           From d_recvmsg.U:

           This  variable conditionally defines the "HAS_RECVMSG" symbol, which
           indicates to the C program that the recvmsg() routine is available.

       "d_regcmp"
           From d_regcmp.U:

           This variable conditionally defines the "HAS_REGCMP"  symbol,  which
           indicates  to  the  C program that the regcmp() routine is available
           for regular pattern matching (usually on System V).

       "d_regcomp"
           From d_regcmp.U:

           This variable conditionally defines the "HAS_REGCOMP" symbol,  which
           indicates  to  the C program that the regcomp() routine is available
           for  regular  pattern  matching  (usually  on   POSIX.2   conforming
           systems).

       "d_remainder"
           From d_remainder.U:

           This  variable  conditionally  defines  the  "HAS_REMAINDER" symbol,
           which indicates to the C program that  the  remainder()  routine  is
           available.

       "d_remquo"
           From d_remquo.U:

           This  variable  conditionally defines the "HAS_REMQUO" symbol, which
           indicates to the C program that the remquo() routine is available.

       "d_rename"
           From d_rename.U:

           This variable conditionally defines the "HAS_RENAME"  symbol,  which
           indicates to the C program that the rename() routine is available to
           rename files.

       "d_renameat"
           From d_fsat.U:

           This variable conditionally defines the "HAS_RENAMEAT" symbol, which
           indicates the "POSIX" renameat() function is available.

       "d_rewinddir"
           From d_readdir.U:

           This  variable  conditionally defines "HAS_REWINDDIR" if rewinddir()
           is available.

       "d_rint"
           From d_rint.U:

           This variable conditionally defines  the  "HAS_RINT"  symbol,  which
           indicates to the C program that the rint() routine is available.

       "d_rmdir"
           From d_rmdir.U:

           This  variable  conditionally  defines  "HAS_RMDIR"  if  rmdir()  is
           available to remove directories.

       "d_round"
           From d_round.U:

           This variable conditionally defines the  "HAS_ROUND"  symbol,  which
           indicates to the C program that the round() routine is available.

       "d_sbrkproto"
           From d_sbrkproto.U:

           This  variable  conditionally  defines  the "HAS_SBRK_PROTO" symbol,
           which indicates  to  the  C  program  that  the  system  provides  a
           prototype  for  the  sbrk()  function.   Otherwise,  it is up to the
           program to supply one.

       "d_scalbn"
           From d_scalbn.U:

           This variable conditionally defines the "HAS_SCALBN"  symbol,  which
           indicates to the C program that the scalbn() routine is available.

       "d_scalbnl"
           From d_scalbnl.U:

           This  variable conditionally defines the "HAS_SCALBNL" symbol, which
           indicates to the C program that the scalbnl() routine is  available.
           If ilogbl is also present we can emulate frexpl.

       "d_sched_yield"
           From d_pthread_y.U:

           This  variable conditionally defines the "HAS_SCHED_YIELD" symbol if
           the sched_yield routine is available to yield the execution  of  the
           current thread.

       "d_scm_rights"
           From d_socket.U:

           This  variable  conditionally  defines  the "HAS_SCM_RIGHTS" symbol,
           which indicates that the "SCM_RIGHTS" is available.  #ifdef  is  not
           enough because it may be an enum, glibc has been known to do this.

       "d_seekdir"
           From d_readdir.U:

           This  variable  conditionally  defines "HAS_SEEKDIR" if seekdir() is
           available.

       "d_select"
           From d_select.U:

           This variable conditionally  defines  "HAS_SELECT"  if  select()  is
           available   to   select  active  file  descriptors.  A  <sys/time.h>
           inclusion may be necessary for the timeout field.

       "d_sem"
           From d_sem.U:

           This variable conditionally  defines  the  "HAS_SEM"  symbol,  which
           indicates that the entire sem*(2) library is present.

       "d_semctl"
           From d_semctl.U:

           This  variable  conditionally defines the "HAS_SEMCTL" symbol, which
           indicates to the C program that the semctl() routine is available.

       "d_semctl_semid_ds"
           From d_union_semun.U:

           This variable  conditionally  defines  "USE_SEMCTL_SEMID_DS",  which
           indicates   that  struct  semid_ds  *  is  to  be  used  for  semctl
           "IPC_STAT".

       "d_semctl_semun"
           From d_union_semun.U:

           This  variable  conditionally  defines   "USE_SEMCTL_SEMUN",   which
           indicates that union semun is to be used for semctl "IPC_STAT".

       "d_semget"
           From d_semget.U:

           This  variable  conditionally defines the "HAS_SEMGET" symbol, which
           indicates to the C program that the semget() routine is available.

       "d_semop"
           From d_semop.U:

           This variable conditionally defines the  "HAS_SEMOP"  symbol,  which
           indicates to the C program that the semop() routine is available.

       "d_sendmsg"
           From d_sendmsg.U:

           This  variable conditionally defines the "HAS_SENDMSG" symbol, which
           indicates to the C program that the sendmsg() routine is available.

       "d_setegid"
           From d_setegid.U:

           This variable conditionally defines the "HAS_SETEGID" symbol,  which
           indicates  to  the C program that the setegid() routine is available
           to change the effective gid of the current program.

       "d_setenv"
           From d_setenv.U:

           This variable conditionally defines the "HAS_SETENV"  symbol,  which
           indicates to the C program that the setenv routine is available.

       "d_seteuid"
           From d_seteuid.U:

           This  variable conditionally defines the "HAS_SETEUID" symbol, which
           indicates to the C program that the seteuid() routine  is  available
           to change the effective uid of the current program.

       "d_setgrent"
           From d_setgrent.U:

           This variable conditionally defines the "HAS_SETGRENT" symbol, which
           indicates  to the C program that the setgrent() routine is available
           for initializing sequential access to the group database.

       "d_setgrent_r"
           From d_setgrent_r.U:

           This variable conditionally  defines  the  "HAS_SETGRENT_R"  symbol,
           which  indicates  to  the C program that the setgrent_r() routine is
           available.

       "d_setgrps"
           From d_setgrps.U:

           This variable  conditionally  defines  the  "HAS_SETGROUPS"  symbol,
           which  indicates  to  the  C program that the setgroups() routine is
           available to set the list of process groups.

       "d_sethent"
           From d_sethent.U:

           This variable conditionally defines "HAS_SETHOSTENT" if sethostent()
           is available.

       "d_sethostent_r"
           From d_sethostent_r.U:

           This variable conditionally defines the  "HAS_SETHOSTENT_R"  symbol,
           which  indicates to the C program that the sethostent_r() routine is
           available.

       "d_setitimer"
           From d_setitimer.U:

           This variable  conditionally  defines  the  "HAS_SETITIMER"  symbol,
           which  indicates  to  the  C program that the setitimer() routine is
           available.

       "d_setlinebuf"
           From d_setlnbuf.U:

           This variable conditionally  defines  the  "HAS_SETLINEBUF"  symbol,
           which  indicates  to  the C program that the setlinebuf() routine is
           available  to  change  stderr  or  stdout  from  block-buffered   or
           unbuffered to a line-buffered mode.

       "d_setlocale"
           From d_setlocale.U:

           This  variable  conditionally defines "HAS_SETLOCALE" if setlocale()
           is available to handle locale-specific ctype implementations.

       "d_setlocale_accepts_any_locale_name"
           From d_setlocale.U:

           This            variable            conditionally            defines
           "SETLOCALE_ACCEPTS_ANY_LOCALE_NAME"   if   setlocale()  accepts  any
           locale name.

       "d_setlocale_r"
           From d_setlocale_r.U:

           This variable conditionally defines  the  "HAS_SETLOCALE_R"  symbol,
           which  indicates  to the C program that the setlocale_r() routine is
           available.

       "d_setnent"
           From d_setnent.U:

           This variable conditionally defines "HAS_SETNETENT"  if  setnetent()
           is available.

       "d_setnetent_r"
           From d_setnetent_r.U:

           This  variable  conditionally  defines the "HAS_SETNETENT_R" symbol,
           which indicates to the C program that the setnetent_r()  routine  is
           available.

       "d_setpent"
           From d_setpent.U:

           This    variable    conditionally   defines   "HAS_SETPROTOENT"   if
           setprotoent() is available.

       "d_setpgid"
           From d_setpgid.U:

           This variable conditionally defines the "HAS_SETPGID" symbol if  the
           setpgid(pid, gpid) function is available to set process group "ID".

       "d_setpgrp"
           From d_setpgrp.U:

           This  variable  conditionally  defines "HAS_SETPGRP" if setpgrp() is
           available to set the current process group.

       "d_setpgrp2"
           From d_setpgrp2.U:

           This variable conditionally defines the HAS_SETPGRP2  symbol,  which
           indicates  to  the  C  program  that  the setpgrp2() (as in DG/"UX")
           routine is available to set the current process group.

       "d_setprior"
           From d_setprior.U:

           This   variable   conditionally   defines    "HAS_SETPRIORITY"    if
           setpriority() is available to set a process's priority.

       "d_setproctitle"
           From d_setproctitle.U:

           This  variable  conditionally defines the "HAS_SETPROCTITLE" symbol,
           which indicates to the C program that the setproctitle() routine  is
           available.

       "d_setprotoent_r"
           From d_setprotoent_r.U:

           This  variable conditionally defines the "HAS_SETPROTOENT_R" symbol,
           which indicates to the C program that the setprotoent_r() routine is
           available.

       "d_setpwent"
           From d_setpwent.U:

           This variable conditionally defines the "HAS_SETPWENT" symbol, which
           indicates to the C program that the setpwent() routine is  available
           for initializing sequential access to the passwd database.

       "d_setpwent_r"
           From d_setpwent_r.U:

           This  variable  conditionally  defines  the "HAS_SETPWENT_R" symbol,
           which indicates to the C program that the  setpwent_r()  routine  is
           available.

       "d_setregid"
           From d_setregid.U:

           This  variable conditionally defines "HAS_SETREGID" if setregid() is
           available to change the  real  and  effective  gid  of  the  current
           process.

       "d_setresgid"
           From d_setregid.U:

           This  variable  conditionally defines "HAS_SETRESGID" if setresgid()
           is available to change the real, effective  and  saved  gid  of  the
           current process.

       "d_setresuid"
           From d_setreuid.U:

           This variable conditionally defines "HAS_SETREUID" if setresuid() is
           available to change the real, effective and saved uid of the current
           process.

       "d_setreuid"
           From d_setreuid.U:

           This  variable conditionally defines "HAS_SETREUID" if setreuid() is
           available to change the  real  and  effective  uid  of  the  current
           process.

       "d_setrgid"
           From d_setrgid.U:

           This  variable conditionally defines the "HAS_SETRGID" symbol, which
           indicates to the C program that the setrgid() routine  is  available
           to change the real gid of the current program.

       "d_setruid"
           From d_setruid.U:

           This  variable conditionally defines the "HAS_SETRUID" symbol, which
           indicates to the C program that the setruid() routine  is  available
           to change the real uid of the current program.

       "d_setsent"
           From d_setsent.U:

           This variable conditionally defines "HAS_SETSERVENT" if setservent()
           is available.

       "d_setservent_r"
           From d_setservent_r.U:

           This  variable  conditionally defines the "HAS_SETSERVENT_R" symbol,
           which indicates to the C program that the setservent_r() routine  is
           available.

       "d_setsid"
           From d_setsid.U:

           This  variable  conditionally  defines  "HAS_SETSID"  if setsid() is
           available to set the process group "ID".

       "d_setvbuf"
           From d_setvbuf.U:

           This variable conditionally defines the "HAS_SETVBUF" symbol,  which
           indicates  to  the C program that the setvbuf() routine is available
           to change buffering on an open stdio stream.

       "d_shm"
           From d_shm.U:

           This variable conditionally  defines  the  "HAS_SHM"  symbol,  which
           indicates that the entire shm*(2) library is present.

       "d_shmat"
           From d_shmat.U:

           This  variable  conditionally  defines the "HAS_SHMAT" symbol, which
           indicates to the C program that the shmat() routine is available.

       "d_shmatprototype"
           From d_shmat.U:

           This  variable  conditionally  defines   the   "HAS_SHMAT_PROTOTYPE"
           symbol, which indicates that sys/shm.h has a prototype for shmat.

       "d_shmctl"
           From d_shmctl.U:

           This  variable  conditionally defines the "HAS_SHMCTL" symbol, which
           indicates to the C program that the shmctl() routine is available.

       "d_shmdt"
           From d_shmdt.U:

           This variable conditionally defines the  "HAS_SHMDT"  symbol,  which
           indicates to the C program that the shmdt() routine is available.

       "d_shmget"
           From d_shmget.U:

           This  variable  conditionally defines the "HAS_SHMGET" symbol, which
           indicates to the C program that the shmget() routine is available.

       "d_sigaction"
           From d_sigaction.U:

           This variable  conditionally  defines  the  "HAS_SIGACTION"  symbol,
           which indicates that the Vr4 sigaction() routine is available.

       "d_siginfo_si_addr"
           From d_siginfo_si.U:

           This   variable   conditionally  defines  the  "HAS_SIGINFO_SI_ADDR"
           symbol, which indicates that the siginfo_t struct  has  the  si_addr
           member.

       "d_siginfo_si_band"
           From d_siginfo_si.U:

           This   variable   conditionally  defines  the  "HAS_SIGINFO_SI_BAND"
           symbol, which indicates that the siginfo_t struct  has  the  si_band
           member.

       "d_siginfo_si_errno"
           From d_siginfo_si.U:

           This   variable  conditionally  defines  the  "HAS_SIGINFO_SI_ERRNO"
           symbol, which indicates that the siginfo_t struct has  the  si_errno
           member.

       "d_siginfo_si_fd"
           From d_siginfo_si.U:

           This  variable conditionally defines the "HAS_SIGINFO_SI_FD" symbol,
           which indicates that the siginfo_t struct has the si_fd member.

       "d_siginfo_si_pid"
           From d_siginfo_si.U:

           This variable conditionally defines the "HAS_SIGINFO_SI_PID" symbol,
           which indicates that the siginfo_t struct has the si_pid member.

       "d_siginfo_si_status"
           From d_siginfo_si.U:

           This  variable  conditionally  defines  the  "HAS_SIGINFO_SI_STATUS"
           symbol,  which indicates that the siginfo_t struct has the si_status
           member.

       "d_siginfo_si_uid"
           From d_siginfo_si.U:

           This variable conditionally defines the "HAS_SIGINFO_SI_UID" symbol,
           which indicates that the siginfo_t struct has the si_uid member.

       "d_siginfo_si_value"
           From d_siginfo_si.U:

           This  variable  conditionally  defines  the   "HAS_SIGINFO_SI_VALUE"
           symbol,  which  indicates that the siginfo_t struct has the si_value
           member.

       "d_signbit"
           From d_signbit.U:

           This variable conditionally defines the "HAS_SIGNBIT" symbol,  which
           indicates  to  the C program that the signbit() routine is available
           and safe to use with perl's intern "NV" type.

       "d_sigprocmask"
           From d_sigprocmask.U:

           This   variable   conditionally   defines    "HAS_SIGPROCMASK"    if
           sigprocmask()  is  available to examine or change the signal mask of
           the calling process.

       "d_sigsetjmp"
           From d_sigsetjmp.U:

           This variable  conditionally  defines  the  "HAS_SIGSETJMP"  symbol,
           which  indicates  that  the sigsetjmp() routine is available to call
           setjmp() and optionally save the process's signal mask.

       "d_sin6_scope_id"
           From d_socket.U:

           This variable conditionally defines  the  HAS_SIN6_SCOPE_ID  symbol,
           which  indicates  that  a  struct  sockaddr_in6  structure  has  the
           sin6_scope_id member.

       "d_sitearch"
           From sitearch.U:

           This variable conditionally defines "SITEARCH" to hold the  pathname
           of  architecture-dependent library files for $package.  If $sitearch
           is the same as $archlib, then this is set to undef.

       "d_snprintf"
           From d_snprintf.U:

           This variable conditionally defines the "HAS_SNPRINTF" symbol, which
           indicates to the C program that the snprintf () library function  is
           available.

       "d_sockaddr_in6"
           From d_socket.U:

           This  variable  conditionally  defines  the HAS_SOCKADDR_IN6 symbol,
           which indicates the availability of a struct sockaddr_in6.

       "d_sockaddr_sa_len"
           From d_socket.U:

           This  variable  conditionally  defines   the   "HAS_SOCKADDR_SA_LEN"
           symbol,  which  indicates  that  a struct sockaddr structure has the
           sa_len member.

       "d_sockaddr_storage"
           From d_socket.U:

           This  variable  conditionally  defines  the   "HAS_SOCKADDR_STORAGE"
           symbol,    which    indicates   the   availability   of   a   struct
           sockaddr_storage.

       "d_sockatmark"
           From d_sockatmark.U:

           This variable conditionally  defines  the  "HAS_SOCKATMARK"  symbol,
           which  indicates  to  the C program that the sockatmark() routine is
           available.

       "d_sockatmarkproto"
           From d_sockatmarkproto.U:

           This  variable  conditionally  defines  the   "HAS_SOCKATMARK_PROTO"
           symbol,  which indicates to the C program that the system provides a
           prototype for the sockatmark() function.  Otherwise, it is up to the
           program to supply one.

       "d_socket"
           From d_socket.U:

           This variable conditionally defines  "HAS_SOCKET",  which  indicates
           that the "BSD" socket interface is supported.

       "d_socklen_t"
           From d_socklen_t.U:

           This symbol will be defined if the C compiler supports socklen_t.

       "d_sockpair"
           From d_socket.U:

           This  variable  conditionally  defines  the "HAS_SOCKETPAIR" symbol,
           which indicates that the "BSD" socketpair() is supported.

       "d_socks5_init"
           From d_socks5_init.U:

           This variable  conditionally  defines  the  HAS_SOCKS5_INIT  symbol,
           which  indicates  to the C program that the socks5_init() routine is
           available.

       "d_sqrtl"
           From d_sqrtl.U:

           This variable conditionally defines the  "HAS_SQRTL"  symbol,  which
           indicates to the C program that the sqrtl() routine is available.

       "d_srand48_r"
           From d_srand48_r.U:

           This  variable conditionally defines the HAS_SRAND48_R symbol, which
           indicates  to  the  C  program  that  the  srand48_r()  routine   is
           available.

       "d_srandom_r"
           From d_srandom_r.U:

           This  variable  conditionally  defines  the  "HAS_SRANDOM_R" symbol,
           which indicates to the C program that  the  srandom_r()  routine  is
           available.

       "d_sresgproto"
           From d_sresgproto.U:

           This   variable   conditionally  defines  the  "HAS_SETRESGID_PROTO"
           symbol, which indicates to the C program that the system provides  a
           prototype  for the setresgid() function.  Otherwise, it is up to the
           program to supply one.

       "d_sresuproto"
           From d_sresuproto.U:

           This  variable  conditionally  defines   the   "HAS_SETRESUID_PROTO"
           symbol,  which indicates to the C program that the system provides a
           prototype for the setresuid() function.  Otherwise, it is up to  the
           program to supply one.

       "d_stat"
           From d_stat.U:

           This   variable   conditionally  defines  "HAS_STAT"  if  stat()  is
           available to get file status.

       "d_statblks"
           From d_statblks.U:

           This variable conditionally defines "USE_STAT_BLOCKS" if this system
           has a stat structure declaring st_blksize and st_blocks.

       "d_statfs_f_flags"
           From d_statfs_f_flags.U:

           This variable conditionally defines the  "HAS_STRUCT_STATFS_F_FLAGS"
           symbol,  which  indicates  to struct statfs from has f_flags member.
           This kind of struct statfs is coming from sys/mount.h  ("BSD"),  not
           from sys/statfs.h ("SYSV").

       "d_statfs_s"
           From d_statfs_s.U:

           This  variable conditionally defines the "HAS_STRUCT_STATFS" symbol,
           which indicates that the struct statfs is supported.

       "d_static_inline"
           From d_static_inline.U:

           This variable conditionally defines the "HAS_STATIC_INLINE"  symbol,
           which  indicates  that  the  C  compiler  supports  C99-style static
           inline.   That  is,  the  function  can't  be  called  from  another
           translation unit.

       "d_statvfs"
           From d_statvfs.U:

           This  variable conditionally defines the "HAS_STATVFS" symbol, which
           indicates to the C program that the statvfs() routine is available.

       "d_stdio_cnt_lval"
           From d_stdstdio.U:

           This  variable  conditionally  defines  "STDIO_CNT_LVALUE"  if   the
           "FILE_cnt" macro can be used as an lvalue.

       "d_stdio_ptr_lval"
           From d_stdstdio.U:

           This   variable  conditionally  defines  "STDIO_PTR_LVALUE"  if  the
           "FILE_ptr" macro can be used as an lvalue.

       "d_stdio_ptr_lval_nochange_cnt"
           From d_stdstdio.U:

           This symbol is defined if using the "FILE_ptr" macro as an lvalue to
           increase the pointer by n leaves File_cnt(fp) unchanged.

       "d_stdio_ptr_lval_sets_cnt"
           From d_stdstdio.U:

           This symbol is defined if using the "FILE_ptr" macro as an lvalue to
           increase the pointer by n has the  side  effect  of  decreasing  the
           value of File_cnt(fp) by n.

       "d_stdio_stream_array"
           From stdio_streams.U:

           This  variable  tells  whether  there  is an array holding the stdio
           streams.

       "d_stdiobase"
           From d_stdstdio.U:

           This variable conditionally defines "USE_STDIO_BASE" if this  system
           has   a   "FILE"  structure  declaring  a  usable  _base  field  (or
           equivalent) in stdio.h.

       "d_stdstdio"
           From d_stdstdio.U:

           This variable conditionally defines "USE_STDIO_PTR" if  this  system
           has  a  "FILE"  structure  declaring usable _ptr and _cnt fields (or
           equivalent) in stdio.h.

       "d_strcoll"
           From d_strcoll.U:

           This variable conditionally defines "HAS_STRCOLL"  if  strcoll()  is
           available to compare strings using collating information.

       "d_strerror_l"
           From d_strerror_l.U:

           This  variable  conditionally  defines  the "HAS_STRERROR_L" symbol,
           which indicates to the C program that the  strerror_l()  routine  is
           available  to  return the error message for a given errno value in a
           particular locale (identified by a locale_t object).

       "d_strerror_r"
           From d_strerror_r.U:

           This variable conditionally  defines  the  "HAS_STRERROR_R"  symbol,
           which  indicates  to  the C program that the strerror_r() routine is
           available.

       "d_strftime"
           From d_strftime.U:

           This variable conditionally defines the "HAS_STRFTIME" symbol, which
           indicates to the C program that the strftime() routine is available.

       "d_strlcat"
           From d_strlcat.U:

           This variable conditionally defines the "HAS_STRLCAT" symbol,  which
           indicates to the C program that the strlcat () routine is available.

       "d_strlcpy"
           From d_strlcpy.U:

           This  variable conditionally defines the "HAS_STRLCPY" symbol, which
           indicates to the C program that the strlcpy () routine is available.

       "d_strnlen"
           From d_strnlen.U:

           This variable conditionally defines the "HAS_STRNLEN" symbol,  which
           indicates to the C program that the strnlen () routine is available.

       "d_strtod"
           From d_strtod.U:

           This  variable  conditionally defines the "HAS_STRTOD" symbol, which
           indicates to the C program that the strtod() routine is available to
           provide better numeric string conversion than atof().

       "d_strtod_l"
           From d_strtod_l.U:

           This variable conditionally defines the "HAS_STRTOD_L" symbol, which
           indicates to the C program that the strtod_l() routine is available.

       "d_strtol"
           From d_strtol.U:

           This variable conditionally defines the "HAS_STRTOL"  symbol,  which
           indicates to the C program that the strtol() routine is available to
           provide better numeric string conversion than atoi() and friends.

       "d_strtold"
           From d_strtold.U:

           This  variable conditionally defines the "HAS_STRTOLD" symbol, which
           indicates to the C program that the strtold() routine is available.

       "d_strtold_l"
           From d_strtold_l.U:

           This variable  conditionally  defines  the  "HAS_STRTOLD_L"  symbol,
           which  indicates  to  the  C program that the strtold_l() routine is
           available.

       "d_strtoll"
           From d_strtoll.U:

           This variable conditionally defines the "HAS_STRTOLL" symbol,  which
           indicates to the C program that the strtoll() routine is available.

       "d_strtoq"
           From d_strtoq.U:

           This  variable  conditionally defines the "HAS_STRTOQ" symbol, which
           indicates to the C program that the strtoq() routine is available.

       "d_strtoul"
           From d_strtoul.U:

           This variable conditionally defines the "HAS_STRTOUL" symbol,  which
           indicates  to  the C program that the strtoul() routine is available
           to provide conversion of strings to unsigned long.

       "d_strtoull"
           From d_strtoull.U:

           This variable conditionally defines the "HAS_STRTOULL" symbol, which
           indicates to the C program that the strtoull() routine is available.

       "d_strtouq"
           From d_strtouq.U:

           This variable conditionally defines the "HAS_STRTOUQ" symbol,  which
           indicates to the C program that the strtouq() routine is available.

       "d_strxfrm"
           From d_strxfrm.U:

           This  variable  conditionally  defines "HAS_STRXFRM" if strxfrm() is
           available to transform strings.

       "d_strxfrm_l"
           From d_strxfrm_l.U:

           This variable conditionally defines "HAS_STRXFRM_L"  if  strxfrm_l()
           is available to transform strings.

       "d_suidsafe"
           From d_dosuid.U:

           This  variable conditionally defines "SETUID_SCRIPTS_ARE_SECURE_NOW"
           if setuid scripts can be secure.  This test looks in /dev/fd/.

       "d_symlink"
           From d_symlink.U:

           This variable conditionally defines the "HAS_SYMLINK" symbol,  which
           indicates  to  the C program that the symlink() routine is available
           to create symbolic links.

       "d_syscall"
           From d_syscall.U:

           This variable conditionally defines "HAS_SYSCALL"  if  syscall()  is
           available call arbitrary system calls.

       "d_syscallproto"
           From d_syscallproto.U:

           This  variable conditionally defines the "HAS_SYSCALL_PROTO" symbol,
           which indicates  to  the  C  program  that  the  system  provides  a
           prototype  for  the  syscall() function.  Otherwise, it is up to the
           program to supply one.

       "d_sysconf"
           From d_sysconf.U:

           This variable conditionally defines the "HAS_SYSCONF" symbol,  which
           indicates  to  the C program that the sysconf() routine is available
           to determine system related limits and options.

       "d_sysernlst"
           From d_strerror.U:

           This   variable   conditionally   defines   "HAS_SYS_ERRNOLIST"   if
           sys_errnolist[]  is  available  to  translate  error  numbers to the
           symbolic name.

       "d_syserrlst"
           From d_strerror.U:

           This   variable   conditionally   defines    "HAS_SYS_ERRLIST"    if
           sys_errlist[] is available to translate error numbers to strings.

       "d_system"
           From d_system.U:

           This  variable  conditionally  defines  "HAS_SYSTEM"  if system() is
           available to issue a shell command.

       "d_tcgetpgrp"
           From d_tcgtpgrp.U:

           This variable  conditionally  defines  the  "HAS_TCGETPGRP"  symbol,
           which  indicates  to  the  C program that the tcgetpgrp() routine is
           available.  to get foreground process group "ID".

       "d_tcsetpgrp"
           From d_tcstpgrp.U:

           This variable  conditionally  defines  the  "HAS_TCSETPGRP"  symbol,
           which  indicates  to  the  C program that the tcsetpgrp() routine is
           available to set foreground process group "ID".

       "d_telldir"
           From d_readdir.U:

           This variable conditionally defines "HAS_TELLDIR"  if  telldir()  is
           available.

       "d_telldirproto"
           From d_telldirproto.U:

           This  variable conditionally defines the "HAS_TELLDIR_PROTO" symbol,
           which indicates  to  the  C  program  that  the  system  provides  a
           prototype  for  the  telldir() function.  Otherwise, it is up to the
           program to supply one.

       "d_tgamma"
           From d_tgamma.U:

           This variable conditionally defines the "HAS_TGAMMA"  symbol,  which
           indicates  to  the  C program that the tgamma() routine is available
           for the gamma function.  See also d_lgamma.

       "d_thread_local"
           From d_thread_local.U:

           This variable conditionally defines the "PERL_THREAD_LOCAL"  symbol.
           In turn that gives a linkage specification for thread-local storage.

       "d_time"
           From d_time.U:

           This  variable  conditionally  defines  the "HAS_TIME" symbol, which
           indicates that the time() routine exists.   The  time()  routine  is
           normally provided on "UNIX" systems.

       "d_timegm"
           From d_timegm.U:

           This  variable  conditionally defines the "HAS_TIMEGM" symbol, which
           indicates to the C program that the timegm () routine is available.

       "d_times"
           From d_times.U:

           This variable conditionally defines the  "HAS_TIMES"  symbol,  which
           indicates  that  the times() routine exists.  The times() routine is
           normally provided  on  "UNIX"  systems.  You  may  have  to  include
           <sys/times.h>.

       "d_tm_tm_gmtoff"
           From i_time.U:

           This   variable   conditionally  defines  "HAS_TM_TM_GMTOFF",  which
           indicates to the C program that the  struct  tm  has  the  tm_gmtoff
           field.

       "d_tm_tm_zone"
           From i_time.U:

           This   variable   conditionally   defines   "HAS_TM_TM_ZONE",  which
           indicates to the C program that the struct tm has the tm_zone field.

       "d_tmpnam_r"
           From d_tmpnam_r.U:

           This variable conditionally defines the "HAS_TMPNAM_R" symbol, which
           indicates to the C program that the tmpnam_r() routine is available.

       "d_towlower"
           From d_towlower.U:

           This variable conditionally defines the "HAS_TOWLOWER" symbol, which
           indicates to the C program that the towlower() routine is available.

       "d_towupper"
           From d_towupper.U:

           This variable conditionally defines the "HAS_TOWUPPER" symbol, which
           indicates to the C program that the towupper() routine is available.

       "d_trunc"
           From d_trunc.U:

           This variable conditionally defines the  "HAS_TRUNC"  symbol,  which
           indicates  to the C program that the trunc() routine is available to
           round doubles towards zero.

       "d_truncate"
           From d_truncate.U:

           This variable conditionally defines "HAS_TRUNCATE" if truncate()  is
           available to truncate files.

       "d_truncl"
           From d_truncl.U:

           This  variable  conditionally defines the "HAS_TRUNCL" symbol, which
           indicates to the C program that the truncl() routine is available to
           round long doubles towards zero. If copysignl is  also  present,  we
           can emulate modfl.

       "d_ttyname_r"
           From d_ttyname_r.U:

           This  variable  conditionally  defines  the  "HAS_TTYNAME_R" symbol,
           which indicates to the C program that  the  ttyname_r()  routine  is
           available.

       "d_tzname"
           From d_tzname.U:

           This  variable  conditionally  defines  "HAS_TZNAME"  if tzname[] is
           available to access timezone names.

       "d_u32align"
           From d_u32align.U:

           This variable tells whether you must access character  data  through
           U32-aligned pointers.

       "d_ualarm"
           From d_ualarm.U:

           This  variable  conditionally defines the "HAS_UALARM" symbol, which
           indicates to the C program that the ualarm() routine is available.

       "d_umask"
           From d_umask.U:

           This variable conditionally defines the  "HAS_UMASK"  symbol,  which
           indicates  to  the  C program that the umask() routine is available.
           to set and get the value of the file creation mask.

       "d_uname"
           From d_gethname.U:

           This variable conditionally defines the  "HAS_UNAME"  symbol,  which
           indicates  to  the C program that the uname() routine may be used to
           derive the host name.

       "d_union_semun"
           From d_union_semun.U:

           This variable conditionally defines "HAS_UNION_SEMUN" if  the  union
           semun is defined by including <sys/sem.h>.

       "d_unlinkat"
           From d_fsat.U:

           This variable conditionally defines the "HAS_UNLINKAT" symbol, which
           indicates the "POSIX" unlinkat() function isavailable.

       "d_unordered"
           From d_unordered.U:

           This  variable  conditionally  defines  the  "HAS_UNORDERED" symbol,
           which indicates to the C program that  the  unordered()  routine  is
           available.

       "d_unsetenv"
           From d_unsetenv.U:

           This variable conditionally defines the "HAS_UNSETENV" symbol, which
           indicates  to  the  C  program  that  the  unsetenv  ()  routine  is
           available.

       "d_uselocale"
           From d_newlocale.U:

           This variable  conditionally  defines  the  "HAS_USELOCALE"  symbol,
           which  indicates  to  the  C program that the uselocale() routine is
           available to set the current locale for the calling thread.

       "d_usleep"
           From d_usleep.U:

           This variable conditionally  defines  "HAS_USLEEP"  if  usleep()  is
           available to do high granularity sleeps.

       "d_usleepproto"
           From d_usleepproto.U:

           This  variable  conditionally defines the "HAS_USLEEP_PROTO" symbol,
           which indicates  to  the  C  program  that  the  system  provides  a
           prototype  for  the  usleep()  function.  Otherwise, it is up to the
           program to supply one.

       "d_ustat"
           From d_ustat.U:

           This  variable  conditionally  defines  "HAS_USTAT"  if  ustat()  is
           available to query file system statistics by dev_t.

       "d_vendorarch"
           From vendorarch.U:

           This variable conditionally defined "PERL_VENDORARCH".

       "d_vendorbin"
           From vendorbin.U:

           This variable conditionally defines "PERL_VENDORBIN".

       "d_vendorlib"
           From vendorlib.U:

           This variable conditionally defines "PERL_VENDORLIB".

       "d_vendorscript"
           From vendorscript.U:

           This variable conditionally defines "PERL_VENDORSCRIPT".

       "d_vfork"
           From d_vfork.U:

           This  variable  conditionally  defines the "HAS_VFORK" symbol, which
           indicates the vfork() routine is available.

       "d_void_closedir"
           From d_closedir.U:

           This variable conditionally defines  "VOID_CLOSEDIR"  if  closedir()
           does not return a value.

       "d_voidsig"
           From d_voidsig.U:

           This   variable  conditionally  defines  "VOIDSIG"  if  this  system
           declares "void (*signal(...))()" in signal.h.  The old  way  was  to
           declare it as "int (*signal(...))()".

       "d_voidtty"
           From i_sysioctl.U:

           This  variable conditionally defines "USE_IOCNOTTY" to indicate that
           the ioctl() call  with  "TIOCNOTTY"  should  be  used  to  void  tty
           association.   Otherwise  (on "USG" probably), it is enough to close
           the standard file descriptors and do a setpgrp().

       "d_vsnprintf"
           From d_snprintf.U:

           This variable  conditionally  defines  the  "HAS_VSNPRINTF"  symbol,
           which  indicates  to  the  C  program  that the vsnprintf () library
           function is available.

       "d_wait4"
           From d_wait4.U:

           This variable conditionally  defines  the  HAS_WAIT4  symbol,  which
           indicates the wait4() routine is available.

       "d_waitpid"
           From d_waitpid.U:

           This  variable  conditionally  defines "HAS_WAITPID" if waitpid() is
           available to wait for child process.

       "d_wcrtomb"
           From d_wcrtomb.U:

           This variable conditionally defines the "HAS_WCRTOMB" symbol if  the
           wcrtomb()  routine  is  available  to  be  used  to  convert  a wide
           character into a multi-byte character.

       "d_wcscmp"
           From d_wcscmp.U:

           This variable conditionally defines the "HAS_WCSCMP" symbol  if  the
           wcscmp()  routine  is  available  and  can  be  used to compare wide
           character strings.

       "d_wcstombs"
           From d_wcstombs.U:

           This variable conditionally defines the "HAS_WCSTOMBS" symbol, which
           indicates to the C program that the wcstombs() routine is  available
           to convert wide character strings to multibyte strings.

       "d_wcsxfrm"
           From d_wcsxfrm.U:

           This  variable conditionally defines the "HAS_WCSXFRM" symbol if the
           wcsxfrm() routine is available and  can  be  used  to  compare  wide
           character strings.

       "d_wctomb"
           From d_wctomb.U:

           This  variable  conditionally defines the "HAS_WCTOMB" symbol, which
           indicates to the C program that the wctomb() routine is available to
           convert a wide character to a multibyte.

       "d_writev"
           From d_writev.U:

           This variable conditionally defines the "HAS_WRITEV"  symbol,  which
           indicates to the C program that the writev() routine is available.

       "d_xenix"
           From Guess.U:

           This variable conditionally defines the symbol "XENIX", which alerts
           the C program that it runs under Xenix.

       "date"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the date program.  After  Configure  runs,  the
           value is reset to a plain "date" and is not useful.

       "db_hashtype"
           From i_db.U:

           This variable contains the type of the hash structure element in the
           <db.h> header file.  In older versions of "DB", it was int, while in
           newer ones it is u_int32_t.

       "db_prefixtype"
           From i_db.U:

           This  variable  contains the type of the prefix structure element in
           the <db.h> header file.  In older versions  of  "DB",  it  was  int,
           while in newer ones it is size_t.

       "db_version_major"
           From i_db.U:

           This  variable  contains  the  major version number of Berkeley "DB"
           found in the <db.h> header file.

       "db_version_minor"
           From i_db.U:

           This variable contains the minor version  number  of  Berkeley  "DB"
           found  in the <db.h> header file.  For "DB" version 1 this is always
           0.

       "db_version_patch"
           From i_db.U:

           This variable contains the patch version  number  of  Berkeley  "DB"
           found  in the <db.h> header file.  For "DB" version 1 this is always
           0.

       "default_inc_excludes_dot"
           From defaultincdot.U:

           When defined, remove the legacy . from @"INC"

       "direntrytype"
           From i_dirent.U:

           This symbol is set to "struct direct" or "struct  dirent"  depending
           on  whether  dirent  is available or not. You should use this pseudo
           type to portably declare your directory entries.

       "dlext"
           From dlext.U:

           This variable contains the extension that is  to  be  used  for  the
           dynamically loaded modules that perl generates.

       "dlsrc"
           From dlsrc.U:

           This  variable  contains  the  name of the dynamic loading file that
           will be used with the package.

       "doubleinfbytes"
           From infnan.U:

           This variable contains comma-separated list of hexadecimal bytes for
           the double precision infinity.

       "doublekind"
           From longdblfio.U:

           This variable, if defined, encodes the type of a double: 1 =  "IEEE"
           754  32-bit  little  endian,  2  = "IEEE" 754 32-bit big endian, 3 =
           "IEEE" 754 64-bit little endian, 4 = "IEEE" 754 64-bit big endian, 5
           = "IEEE" 754 128-bit little endian,  6  =  "IEEE"  754  128-bit  big
           endian,  7  =  "IEEE"  754 64-bit mixed endian le-be, 8 = "IEEE" 754
           64-bit mixed endian be-le, 9 = "VAX" 32bit  little  endian  F  float
           format  10  =  "VAX"  64bit  little endian D float format 11 = "VAX"
           64bit little endian G float format 12 =  "IBM"  32bit  format  13  =
           "IBM" 64bit format 14 = Cray 64bit format -1 = unknown format.

       "doublemantbits"
           From mantbits.U:

           This  symbol,  if defined, tells how many mantissa bits there are in
           double precision floating point format.  Note that this  is  usually
           "DBL_MANT_DIG" minus one, since with the standard "IEEE" 754 formats
           "DBL_MANT_DIG" includes the implicit bit which doesn't really exist.

       "doublenanbytes"
           From infnan.U:

           This variable contains comma-separated list of hexadecimal bytes for
           the double precision not-a-number.

       "doublesize"
           From doublesize.U:

           This  variable  contains the value of the "DOUBLESIZE" symbol, which
           indicates to the C program how many bytes there are in a double.

       "drand01"
           From randfunc.U:

           Indicates the  macro  to  be  used  to  generate  normalized  random
           numbers.  Uses randfunc, often divided by (double) (((unsigned long)
           1  <<  randbits))  in order to normalize the result.  In C programs,
           the macro "Drand01" is mapped to drand01.

       "drand48_r_proto"
           From d_drand48_r.U:

           This variable encodes the prototype of drand48_r.   It  is  zero  if
           d_drand48_r  is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_drand48_r is defined.

       "dtrace"
           From usedtrace.U:

           This variable holds the location of the dtrace executable.

       "dtraceobject"
           From dtraceobject.U:

           Whether we need to build an object file with the dtrace tool.

       "dtracexnolibs"
           From dtraceobject.U:

           Whether dtrace accepts -xnolibs.  If available we call dtrace -h and
           dtrace -G with -xnolibs to allow dtrace to run in a jail on FreeBSD.

       "dynamic_ext"
           From Extensions.U:

           This variable holds a list of "XS" extension files we want  to  link
           dynamically into the package.  It is used by Makefile.

   e
       "eagain"
           From nblock_io.U:

           This  variable  bears  the symbolic errno code set by read() when no
           data is present  on  the  file  and  non-blocking  I/O  was  enabled
           (otherwise, read() blocks naturally).

       "ebcdic"
           From ebcdic.U:

           This  variable  conditionally  defines  "EBCDIC" if this system uses
           "EBCDIC" encoding.

       "echo"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of the echo program.  After Configure runs, the
           value is reset to a plain "echo" and is not useful.

       "egrep"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any) of the egrep program.  After Configure runs, the
           value is reset to a plain "egrep" and is not useful.

       "emacs"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "endgrent_r_proto"
           From d_endgrent_r.U:

           This  variable  encodes  the prototype of endgrent_r.  It is zero if
           d_endgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_endgrent_r is defined.

       "endhostent_r_proto"
           From d_endhostent_r.U:

           This variable encodes the prototype of endhostent_r.  It is zero  if
           d_endhostent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_endhostent_r is defined.

       "endnetent_r_proto"
           From d_endnetent_r.U:

           This variable encodes the prototype of endnetent_r.  It is  zero  if
           d_endnetent_r  is  undef,  and  one  of  the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_endnetent_r is defined.

       "endprotoent_r_proto"
           From d_endprotoent_r.U:

           This variable encodes the prototype of endprotoent_r.  It is zero if
           d_endprotoent_r is undef, and  one  of  the  "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_endprotoent_r is defined.

       "endpwent_r_proto"
           From d_endpwent_r.U:

           This  variable  encodes  the prototype of endpwent_r.  It is zero if
           d_endpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_endpwent_r is defined.

       "endservent_r_proto"
           From d_endservent_r.U:

           This variable encodes the prototype of endservent_r.  It is zero  if
           d_endservent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_endservent_r is defined.

       "eunicefix"
           From Init.U:

           When running under Eunice this variable  contains  a  command  which
           will  convert  a shell script to the proper form of text file for it
           to be executable by the shell.  On other systems it is a no-op.

       "exe_ext"
           From Unix.U:

           This is an old synonym for _exe.

       "expr"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of the expr program.  After Configure runs, the
           value is reset to a plain "expr" and is not useful.

       "extensions"
           From Extensions.U:

           This variable holds a list of all extension  files  (both  "XS"  and
           non-xs)  installed  with the package.  It is propagated to Config.pm
           and is typically used to test  whether  a  particular  extension  is
           available.

       "extern_C"
           From Csym.U:

           "ANSI"  C  requires  "extern"  where C++ requires 'extern "C"'. This
           variable can be used in Configure to do the right thing.

       "extras"
           From Extras.U:

           This variable holds a list of extra modules to install.

   f
       "fflushNULL"
           From fflushall.U:

           This symbol, if defined, tells that fflush("NULL") correctly flushes
           all pending stdio output without side  effects.  In  particular,  on
           some platforms calling fflush("NULL") *still* corrupts "STDIN" if it
           is a pipe.

       "fflushall"
           From fflushall.U:

           This  symbol,  if  defined,  tells  that  to flush all pending stdio
           output one must loop through all the stdio file handles stored in an
           array  and  fflush  them.   Note  that  if  fflushNULL  is  defined,
           fflushall will not even be probed for and will be left undefined.

       "find"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "firstmakefile"
           From Unix.U:

           This variable defines the first file searched by make.  On unix,  it
           is  makefile (then Makefile).  On case-insensitive systems, it might
           be something else.  This is only used to deal with  convoluted  make
           depend tricks.

       "flex"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "fpossize"
           From fpossize.U:

           This variable contains the size of a fpostype in bytes.

       "fpostype"
           From fpostype.U:

           This variable defines Fpos_t to  be  something  like  fpos_t,  long,
           uint, or whatever type is used to declare file positions in libc.

       "freetype"
           From mallocsrc.U:

           This  variable  contains  the  return type of free().  It is usually
           void, but occasionally int.

       "from"
           From Cross.U:

           This variable contains the command used by Configure to  copy  files
           from  the target host.  Useful and available only during Perl build.
           The string ":" if not cross-compiling.

       "full_ar"
           From Loc_ar.U:

           This variable contains the full pathname to "ar", whether or not the
           user  has  specified  "portability".   This  is  only  used  in  the
           Makefile.SH.

       "full_csh"
           From d_csh.U:

           This  variable  contains  the full pathname to "csh", whether or not
           the user has specified "portability".  This  is  only  used  in  the
           compiled  C  program, and we assume that all systems which can share
           this executable will have the same full pathname to csh.

       "full_sed"
           From Loc_sed.U:

           This variable contains the full pathname to "sed",  whether  or  not
           the  user  has  specified  "portability".   This is only used in the
           compiled C program, and we assume that all systems which  can  share
           this executable will have the same full pathname to sed.

   g
       "gccansipedantic"
           From gccvers.U:

           If  "GNU"  cc  (gcc) is used, this variable will enable (if set) the
           -ansi and -pedantic ccflags for building core files (through  cflags
           script). (See Porting/pumpkin.pod for full description).

       "gccosandvers"
           From gccvers.U:

           If  "GNU" cc (gcc) is used, this variable holds the operating system
           and version used to compile gcc.  It is set to '' if not gcc, or  if
           nothing useful can be parsed as the os version.

       "gccversion"
           From gccvers.U:

           If  "GNU"  cc  (gcc) is used, this variable holds 1 or 2 to indicate
           whether the compiler is version 1 or 2.  This  is  used  in  setting
           some of the default cflags.  It is set to '' if not gcc.

       "getgrent_r_proto"
           From d_getgrent_r.U:

           This  variable  encodes  the prototype of getgrent_r.  It is zero if
           d_getgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getgrent_r is defined.

       "getgrgid_r_proto"
           From d_getgrgid_r.U:

           This variable encodes the prototype of getgrgid_r.  It  is  zero  if
           d_getgrgid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getgrgid_r is defined.

       "getgrnam_r_proto"
           From d_getgrnam_r.U:

           This  variable  encodes  the prototype of getgrnam_r.  It is zero if
           d_getgrnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getgrnam_r is defined.

       "gethostbyaddr_r_proto"
           From d_gethostbyaddr_r.U:

           This variable encodes the prototype of gethostbyaddr_r.  It is  zero
           if     d_gethostbyaddr_r     is    undef,    and    one    of    the
           "REENTRANT_PROTO_T_ABC" macros of reentr.h if  d_gethostbyaddr_r  is
           defined.

       "gethostbyname_r_proto"
           From d_gethostbyname_r.U:

           This  variable encodes the prototype of gethostbyname_r.  It is zero
           if    d_gethostbyname_r    is    undef,    and    one     of     the
           "REENTRANT_PROTO_T_ABC"  macros  of reentr.h if d_gethostbyname_r is
           defined.

       "gethostent_r_proto"
           From d_gethostent_r.U:

           This variable encodes the prototype of gethostent_r.  It is zero  if
           d_gethostent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_gethostent_r is defined.

       "getlogin_r_proto"
           From d_getlogin_r.U:

           This variable encodes the prototype of getlogin_r.  It  is  zero  if
           d_getlogin_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getlogin_r is defined.

       "getnetbyaddr_r_proto"
           From d_getnetbyaddr_r.U:

           This  variable  encodes the prototype of getnetbyaddr_r.  It is zero
           if d_getnetbyaddr_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_getnetbyaddr_r is defined.

       "getnetbyname_r_proto"
           From d_getnetbyname_r.U:

           This variable encodes the prototype of getnetbyname_r.  It  is  zero
           if d_getnetbyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_getnetbyname_r is defined.

       "getnetent_r_proto"
           From d_getnetent_r.U:

           This  variable  encodes the prototype of getnetent_r.  It is zero if
           d_getnetent_r is  undef,  and  one  of  the  "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_getnetent_r is defined.

       "getprotobyname_r_proto"
           From d_getprotobyname_r.U:

           This variable encodes the prototype of getprotobyname_r.  It is zero
           if     d_getprotobyname_r    is    undef,    and    one    of    the
           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobyname_r  is
           defined.

       "getprotobynumber_r_proto"
           From d_getprotobynumber_r.U:

           This  variable  encodes  the prototype of getprotobynumber_r.  It is
           zero  if   d_getprotobynumber_r   is   undef,   and   one   of   the
           "REENTRANT_PROTO_T_ABC"  macros  of reentr.h if d_getprotobynumber_r
           is defined.

       "getprotoent_r_proto"
           From d_getprotoent_r.U:

           This variable encodes the prototype of getprotoent_r.  It is zero if
           d_getprotoent_r is undef, and  one  of  the  "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_getprotoent_r is defined.

       "getpwent_r_proto"
           From d_getpwent_r.U:

           This  variable  encodes  the prototype of getpwent_r.  It is zero if
           d_getpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getpwent_r is defined.

       "getpwnam_r_proto"
           From d_getpwnam_r.U:

           This variable encodes the prototype of getpwnam_r.  It  is  zero  if
           d_getpwnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getpwnam_r is defined.

       "getpwuid_r_proto"
           From d_getpwuid_r.U:

           This  variable  encodes  the prototype of getpwuid_r.  It is zero if
           d_getpwuid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getpwuid_r is defined.

       "getservbyname_r_proto"
           From d_getservbyname_r.U:

           This variable encodes the prototype of getservbyname_r.  It is  zero
           if     d_getservbyname_r     is    undef,    and    one    of    the
           "REENTRANT_PROTO_T_ABC" macros of reentr.h if  d_getservbyname_r  is
           defined.

       "getservbyport_r_proto"
           From d_getservbyport_r.U:

           This  variable encodes the prototype of getservbyport_r.  It is zero
           if    d_getservbyport_r    is    undef,    and    one     of     the
           "REENTRANT_PROTO_T_ABC"  macros  of reentr.h if d_getservbyport_r is
           defined.

       "getservent_r_proto"
           From d_getservent_r.U:

           This variable encodes the prototype of getservent_r.  It is zero  if
           d_getservent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_getservent_r is defined.

       "getspnam_r_proto"
           From d_getspnam_r.U:

           This variable encodes the prototype of getspnam_r.  It  is  zero  if
           d_getspnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_getspnam_r is defined.

       "gidformat"
           From gidf.U:

           This variable contains the format string used for printing a Gid_t.

       "gidsign"
           From gidsign.U:

           This variable contains the signedness of a gidtype.  1 for unsigned,
           -1 for signed.

       "gidsize"
           From gidsize.U:

           This variable contains the size of a gidtype in bytes.

       "gidtype"
           From gidtype.U:

           This variable defines Gid_t to be something like gid_t, int, ushort,
           or  whatever  type  is  used to declare the return type of getgid().
           Typically, it is the type of group ids in the kernel.

       "glibpth"
           From libpth.U:

           This variable holds the general path (space-separated) used to  find
           libraries.   It  may  contain  directories that do not exist on this
           platform, libpth is the cleaned-up version.

       "gmake"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any) of the gmake program.  After Configure runs, the
           value is reset to a plain "gmake" and is not useful.

       "gmtime_r_proto"
           From d_gmtime_r.U:

           This variable encodes the prototype of  gmtime_r.   It  is  zero  if
           d_gmtime_r  is  undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_gmtime_r is defined.

       "gnulibc_version"
           From d_gnulibc.U:

           This variable contains the version number of the  "GNU"  C  library.
           It is usually something like 2.2.5.  It is a plain '' if this is not
           the "GNU" C library, or if the version is unknown.

       "grep"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the grep program.  After  Configure  runs,  the
           value is reset to a plain "grep" and is not useful.

       "groupcat"
           From nis.U:

           This  variable  contains  a  command  that  produces the text of the
           /etc/group file.  This is normally  "cat  /etc/group",  but  can  be
           "ypcat  group"  when "NIS" is used.  On some systems, such as os390,
           there may be no equivalent command, in which case this  variable  is
           unset.

       "groupstype"
           From groupstype.U:

           This  variable  defines  Groups_t  to  be something like gid_t, int,
           ushort, or  whatever  type  is  used  for  the  second  argument  to
           getgroups()  and  setgroups().  Usually, this is the same as gidtype
           (gid_t), but sometimes it isn't.

       "gzip"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of the gzip program.  After Configure runs, the
           value is reset to a plain "gzip" and is not useful.

   h
       "h_fcntl"
           From h_fcntl.U:

           This is variable gets set in various places  to  tell  i_fcntl  that
           <fcntl.h> should be included.

       "h_sysfile"
           From h_sysfile.U:

           This  is variable gets set in various places to tell i_sys_file that
           <sys/file.h> should be included.

       "hint"
           From Oldconfig.U:

           Gives the type of hints used for previous answers.  May  be  one  of
           "default", "recommended" or "previous".

       "hostcat"
           From nis.U:

           This  variable  contains  a  command  that  produces the text of the
           /etc/hosts file.  This is normally  "cat  /etc/hosts",  but  can  be
           "ypcat  hosts"  when "NIS" is used.  On some systems, such as os390,
           there may be no equivalent command, in which case this  variable  is
           unset.

       "hostgenerate"
           From Cross.U:

           This variable contains the path to a generate_uudmap binary that can
           be  run on the host "OS" when cross-compiling.  Useful and available
           only during Perl build.  Empty string '' if not cross-compiling.

       "hostosname"
           From Cross.U:

           This variable contains the original value of $^O for  hostperl  when
           cross-compiling.   This  is  useful  to  pick  the proper tools when
           running build code in the host.   Empty  string  ''  if  not  cross-
           compiling.

       "hostperl"
           From Cross.U:

           This variable contains the path to a miniperl binary that can be run
           on  the  host  "OS" when cross-compiling.  Useful and available only
           during Perl build.  Empty string '' if not cross-compiling.

       "html1dir"
           From html1dir.U:

           This variable contains the name  of  the  directory  in  which  html
           source  pages  are  to  be  put.   This  directory is for pages that
           describe whole programs, not libraries or modules.  It  is  intended
           to correspond roughly to section 1 of the Unix manuals.

       "html1direxp"
           From html1dir.U:

           This  variable is the same as the html1dir variable, but is filename
           expanded at configuration time, for convenient use in makefiles.

       "html3dir"
           From html3dir.U:

           This variable contains the name  of  the  directory  in  which  html
           source  pages  are  to  be  put.   This  directory is for pages that
           describe libraries or modules.  It is intended to correspond roughly
           to section 3 of the Unix manuals.

       "html3direxp"
           From html3dir.U:

           This variable is the same as the html3dir variable, but is  filename
           expanded at configuration time, for convenient use in makefiles.

   i
       "i16size"
           From perlxv.U:

           This variable is the size of an I16 in bytes.

       "i16type"
           From perlxv.U:

           This variable contains the C type used for Perl's I16.

       "i32dformat"
           From perlx32f.U:

           This  variable  contains  the format string used for printing a Perl
           I32 as a signed decimal integer.

       "i32size"
           From perlxv.U:

           This variable is the size of an I32 in bytes.

       "i32type"
           From perlxv.U:

           This variable contains the C type used for Perl's I32.

       "i64size"
           From perlxv.U:

           This variable is the size of an I64 in bytes.

       "i64type"
           From perlxv.U:

           This variable contains the C type used for Perl's I64.

       "i8size"
           From perlxv.U:

           This variable is the size of an I8 in bytes.

       "i8type"
           From perlxv.U:

           This variable contains the C type used for Perl's I8.

       "i_arpainet"
           From i_arpainet.U:

           This variable conditionally defines the  "I_ARPA_INET"  symbol,  and
           indicates whether a C program should include <arpa/inet.h>.

       "i_bfd"
           From i_bfd.U:

           This   variable   conditionally  defines  the  "I_BFD"  symbol,  and
           indicates whether a C program can include <bfd.h>.

       "i_bsdioctl"
           From i_sysioctl.U:

           This variable conditionally  defines  the  "I_SYS_BSDIOCTL"  symbol,
           which  indicates  to  the C program that <sys/bsdioctl.h> exists and
           should be included.

       "i_crypt"
           From i_crypt.U:

           This  variable  conditionally  defines  the  "I_CRYPT"  symbol,  and
           indicates whether a C program should include <crypt.h>.

       "i_db"
           From i_db.U:

           This variable conditionally defines the "I_DB" symbol, and indicates
           whether a C program may include Berkeley's "DB" include file <db.h>.

       "i_dbm"
           From i_dbm.U:

           This  variable  conditionally  defines  the  "I_DBM"  symbol,  which
           indicates to the  C  program  that  <dbm.h>  exists  and  should  be
           included.

       "i_dirent"
           From i_dirent.U:

           This  variable  conditionally defines "I_DIRENT", which indicates to
           the C program that it should include <dirent.h>.

       "i_dlfcn"
           From i_dlfcn.U:

           This variable conditionally  defines  the  "I_DLFCN"  symbol,  which
           indicates  to  the  C  program  that  <dlfcn.h> exists and should be
           included.

       "i_execinfo"
           From i_execinfo.U:

           This variable conditionally defines  the  "I_EXECINFO"  symbol,  and
           indicates   whether  a  C  program  may  include  <execinfo.h>,  for
           backtrace() support.

       "i_fcntl"
           From i_fcntl.U:

           This variable controls the value of "I_FCNTL"  (which  tells  the  C
           program to include <fcntl.h>).

       "i_fenv"
           From i_fenv.U:

           This  variable  conditionally  defines  the  "I_FENV"  symbol, which
           indicates to the C  program  that  <fenv.h>  exists  and  should  be
           included.

       "i_fp"
           From i_fp.U:

           This variable conditionally defines the "I_FP" symbol, and indicates
           whether a C program should include <fp.h>.

       "i_fp_class"
           From i_fp_class.U:

           This  variable  conditionally  defines  the "I_FP_CLASS" symbol, and
           indicates whether a C program should include <fp_class.h>.

       "i_gdbm"
           From i_gdbm.U:

           This variable  conditionally  defines  the  "I_GDBM"  symbol,  which
           indicates  to  the  C  program  that  <gdbm.h>  exists and should be
           included.

       "i_gdbm_ndbm"
           From i_ndbm.U:

           This variable conditionally defines the "I_GDBM_NDBM" symbol,  which
           indicates  to  the C program that <gdbm-ndbm.h> exists and should be
           included.  This is the location of the ndbm.h compatibility file  in
           Debian 4.0.

       "i_gdbmndbm"
           From i_ndbm.U:

           This  variable  conditionally defines the "I_GDBMNDBM" symbol, which
           indicates to the C program that <gdbm/ndbm.h> exists and  should  be
           included.  This was the location of the ndbm.h compatibility file in
           RedHat 7.1.

       "i_grp"
           From i_grp.U:

           This   variable   conditionally  defines  the  "I_GRP"  symbol,  and
           indicates whether a C program should include <grp.h>.

       "i_ieeefp"
           From i_ieeefp.U:

           This variable  conditionally  defines  the  "I_IEEEFP"  symbol,  and
           indicates whether a C program should include <ieeefp.h>.

       "i_inttypes"
           From i_inttypes.U:

           This  variable  conditionally  defines  the "I_INTTYPES" symbol, and
           indicates whether a C program should include <inttypes.h>.

       "i_langinfo"
           From i_langinfo.U:

           This variable conditionally defines  the  "I_LANGINFO"  symbol,  and
           indicates whether a C program should include <langinfo.h>.

       "i_libutil"
           From i_libutil.U:

           This  variable  conditionally  defines  the  "I_LIBUTIL" symbol, and
           indicates whether a C program should include <libutil.h>.

       "i_locale"
           From i_locale.U:

           This variable  conditionally  defines  the  "I_LOCALE"  symbol,  and
           indicates whether a C program should include <locale.h>.

       "i_machcthr"
           From i_machcthr.U:

           This  variable  conditionally  defines the "I_MACH_CTHREADS" symbol,
           and indicates whether a C program should include <mach/cthreads.h>.

       "i_malloc"
           From i_malloc.U:

           This variable  conditionally  defines  the  "I_MALLOC"  symbol,  and
           indicates whether a C program should include <malloc.h>.

       "i_mallocmalloc"
           From i_mallocmalloc.U:

           This variable conditionally defines the "I_MALLOCMALLOC" symbol, and
           indicates whether a C program should include <malloc/malloc.h>.

       "i_mntent"
           From i_mntent.U:

           This  variable  conditionally  defines  the  "I_MNTENT"  symbol, and
           indicates whether a C program should include <mntent.h>.

       "i_ndbm"
           From i_ndbm.U:

           This variable  conditionally  defines  the  "I_NDBM"  symbol,  which
           indicates  to  the  C  program  that  <ndbm.h>  exists and should be
           included.

       "i_netdb"
           From i_netdb.U:

           This  variable  conditionally  defines  the  "I_NETDB"  symbol,  and
           indicates whether a C program should include <netdb.h>.

       "i_neterrno"
           From i_neterrno.U:

           This  variable conditionally defines the "I_NET_ERRNO" symbol, which
           indicates to the C program that <net/errno.h> exists and  should  be
           included.

       "i_netinettcp"
           From i_netinettcp.U:

           This  variable conditionally defines the "I_NETINET_TCP" symbol, and
           indicates whether a C program should include <netinet/tcp.h>.

       "i_niin"
           From i_niin.U:

           This variable conditionally defines "I_NETINET_IN", which  indicates
           to  the  C program that it should include <netinet/in.h>. Otherwise,
           you may try <sys/in.h>.

       "i_poll"
           From i_poll.U:

           This  variable  conditionally  defines  the  "I_POLL"  symbol,   and
           indicates whether a C program should include <poll.h>.

       "i_prot"
           From i_prot.U:

           This   variable  conditionally  defines  the  "I_PROT"  symbol,  and
           indicates whether a C program should include <prot.h>.

       "i_pthread"
           From i_pthread.U:

           This variable conditionally  defines  the  "I_PTHREAD"  symbol,  and
           indicates whether a C program should include <pthread.h>.

       "i_pwd"
           From i_pwd.U:

           This  variable conditionally defines "I_PWD", which indicates to the
           C program that it should include <pwd.h>.

       "i_quadmath"
           From i_quadmath.U:

           This variable conditionally defines "I_QUADMATH", which indicates to
           the C program that it should include <quadmath.h>.

       "i_rpcsvcdbm"
           From i_dbm.U:

           This variable conditionally defines the "I_RPCSVC_DBM" symbol, which
           indicates to the C program that <rpcsvc/dbm.h> exists and should  be
           included.  Some System V systems might need this instead of <dbm.h>.

       "i_sgtty"
           From i_termio.U:

           This  variable  conditionally  defines  the  "I_SGTTY" symbol, which
           indicates to the C program that it should include  <sgtty.h>  rather
           than <termio.h>.

       "i_shadow"
           From i_shadow.U:

           This  variable  conditionally  defines  the  "I_SHADOW"  symbol, and
           indicates whether a C program should include <shadow.h>.

       "i_socks"
           From i_socks.U:

           This  variable  conditionally  defines  the  "I_SOCKS"  symbol,  and
           indicates whether a C program should include <socks.h>.

       "i_stdbool"
           From i_stdbool.U:

           This  variable  conditionally  defines the "I_STDBOOL" symbol, which
           indicates to the C program that <stdbool.h>  exists  and  should  be
           included.

       "i_stdint"
           From i_stdint.U:

           This  variable  conditionally  defines  the "I_STDINT" symbol, which
           indicates to the C program that  <stdint.h>  exists  and  should  be
           included.

       "i_stdlib"
           From i_stdlib.U:

           This variable unconditionally defines the "I_STDLIB" symbol.

       "i_sunmath"
           From i_sunmath.U:

           This  variable  conditionally  defines  the  "I_SUNMATH" symbol, and
           indicates whether a C program should include <sunmath.h>.

       "i_sysaccess"
           From i_sysaccess.U:

           This variable conditionally defines the "I_SYS_ACCESS"  symbol,  and
           indicates whether a C program should include <sys/access.h>.

       "i_sysdir"
           From i_sysdir.U:

           This  variable  conditionally  defines  the  "I_SYS_DIR" symbol, and
           indicates whether a C program should include <sys/dir.h>.

       "i_sysfile"
           From i_sysfile.U:

           This variable conditionally defines  the  "I_SYS_FILE"  symbol,  and
           indicates  whether  a  C  program should include <sys/file.h> to get
           "R_OK" and friends.

       "i_sysfilio"
           From i_sysioctl.U:

           This variable conditionally defines the "I_SYS_FILIO" symbol,  which
           indicates  to  the C program that <sys/filio.h> exists and should be
           included in preference to <sys/ioctl.h>.

       "i_sysin"
           From i_niin.U:

           This variable conditionally defines "I_SYS_IN", which  indicates  to
           the   C  program  that  it  should  include  <sys/in.h>  instead  of
           <netinet/in.h>.

       "i_sysioctl"
           From i_sysioctl.U:

           This variable conditionally defines the "I_SYS_IOCTL" symbol,  which
           indicates  to  the C program that <sys/ioctl.h> exists and should be
           included.

       "i_syslog"
           From i_syslog.U:

           This variable  conditionally  defines  the  "I_SYSLOG"  symbol,  and
           indicates whether a C program should include <syslog.h>.

       "i_sysmman"
           From i_sysmman.U:

           This  variable  conditionally  defines  the "I_SYS_MMAN" symbol, and
           indicates whether a C program should include <sys/mman.h>.

       "i_sysmode"
           From i_sysmode.U:

           This variable conditionally  defines  the  "I_SYSMODE"  symbol,  and
           indicates whether a C program should include <sys/mode.h>.

       "i_sysmount"
           From i_sysmount.U:

           This  variable  conditionally  defines  the "I_SYSMOUNT" symbol, and
           indicates whether a C program should include <sys/mount.h>.

       "i_sysndir"
           From i_sysndir.U:

           This variable conditionally defines  the  "I_SYS_NDIR"  symbol,  and
           indicates whether a C program should include <sys/ndir.h>.

       "i_sysparam"
           From i_sysparam.U:

           This  variable  conditionally  defines the "I_SYS_PARAM" symbol, and
           indicates whether a C program should include <sys/param.h>.

       "i_syspoll"
           From i_syspoll.U:

           This variable conditionally defines the "I_SYS_POLL"  symbol,  which
           indicates to the C program that it should include <sys/poll.h>.

       "i_sysresrc"
           From i_sysresrc.U:

           This variable conditionally defines the "I_SYS_RESOURCE" symbol, and
           indicates whether a C program should include <sys/resource.h>.

       "i_syssecrt"
           From i_syssecrt.U:

           This variable conditionally defines the "I_SYS_SECURITY" symbol, and
           indicates whether a C program should include <sys/security.h>.

       "i_sysselct"
           From i_sysselct.U:

           This  variable conditionally defines "I_SYS_SELECT", which indicates
           to the C program that it should include <sys/select.h> in  order  to
           get the definition of struct timeval.

       "i_syssockio"
           From i_sysioctl.U:

           This  variable  conditionally  defines "I_SYS_SOCKIO" to indicate to
           the C program that socket ioctl codes may be found in <sys/sockio.h>
           instead of <sys/ioctl.h>.

       "i_sysstat"
           From i_sysstat.U:

           This variable conditionally defines  the  "I_SYS_STAT"  symbol,  and
           indicates whether a C program should include <sys/stat.h>.

       "i_sysstatfs"
           From i_sysstatfs.U:

           This  variable  conditionally  defines the "I_SYSSTATFS" symbol, and
           indicates whether a C program should include <sys/statfs.h>.

       "i_sysstatvfs"
           From i_sysstatvfs.U:

           This variable conditionally defines the "I_SYSSTATVFS"  symbol,  and
           indicates whether a C program should include <sys/statvfs.h>.

       "i_syssyscall"
           From i_syssyscall.U:

           This  variable conditionally defines the "I_SYS_SYSCALL" symbol, and
           indicates whether a C program should include <sys/syscall.h>.

       "i_systime"
           From i_time.U:

           This variable conditionally defines "I_SYS_TIME", which indicates to
           the C program that it should include <sys/time.h>.

       "i_systimek"
           From i_time.U:

           This  variable  conditionally  defines  "I_SYS_TIME_KERNEL",   which
           indicates  to the C program that it should include <sys/time.h> with
           "KERNEL" defined.

       "i_systimes"
           From i_systimes.U:

           This variable conditionally defines the  "I_SYS_TIMES"  symbol,  and
           indicates whether a C program should include <sys/times.h>.

       "i_systypes"
           From i_systypes.U:

           This  variable  conditionally  defines the "I_SYS_TYPES" symbol, and
           indicates whether a C program should include <sys/types.h>.

       "i_sysuio"
           From i_sysuio.U:

           This variable  conditionally  defines  the  "I_SYSUIO"  symbol,  and
           indicates whether a C program should include <sys/uio.h>.

       "i_sysun"
           From i_sysun.U:

           This  variable  conditionally defines "I_SYS_UN", which indicates to
           the C program that it should include <sys/un.h> to get "UNIX" domain
           socket definitions.

       "i_sysutsname"
           From i_sysutsname.U:

           This variable conditionally defines the "I_SYSUTSNAME"  symbol,  and
           indicates whether a C program should include <sys/utsname.h>.

       "i_sysvfs"
           From i_sysvfs.U:

           This  variable  conditionally  defines  the  "I_SYSVFS"  symbol, and
           indicates whether a C program should include <sys/vfs.h>.

       "i_syswait"
           From i_syswait.U:

           This variable conditionally defines "I_SYS_WAIT", which indicates to
           the C program that it should include <sys/wait.h>.

       "i_termio"
           From i_termio.U:

           This variable conditionally defines  the  "I_TERMIO"  symbol,  which
           indicates  to the C program that it should include <termio.h> rather
           than <sgtty.h>.

       "i_termios"
           From i_termio.U:

           This variable conditionally defines the  "I_TERMIOS"  symbol,  which
           indicates  to  the C program that the "POSIX" <termios.h> file is to
           be included.

       "i_time"
           From i_time.U:

           This variable unconditionally defines "I_TIME", which  indicates  to
           the C program that it should include <time.h>.

       "i_unistd"
           From i_unistd.U:

           This  variable  conditionally  defines  the  "I_UNISTD"  symbol, and
           indicates whether a C program should include <unistd.h>.

       "i_ustat"
           From i_ustat.U:

           This  variable  conditionally  defines  the  "I_USTAT"  symbol,  and
           indicates whether a C program should include <ustat.h>.

       "i_utime"
           From i_utime.U:

           This  variable  conditionally  defines  the  "I_UTIME"  symbol,  and
           indicates whether a C program should include <utime.h>.

       "i_vfork"
           From i_vfork.U:

           This  variable  conditionally  defines  the  "I_VFORK"  symbol,  and
           indicates whether a C program should include vfork.h.

       "i_wchar"
           From i_wchar.U:

           This  variable  conditionally  defines  the  "I_WCHAR"  symbol, that
           indicates whether a C program may include <wchar.h>.

       "i_wctype"
           From i_wctype.U:

           This variable conditionally  defines  the  "I_WCTYPE"  symbol,  that
           indicates whether a C program may include <wctype.h>.

       "i_xlocale"
           From d_newlocale.U:

           This  symbol, if defined, indicates to the C program that the header
           xlocale.h is available.  See also xlocale_needed.

       "ignore_versioned_solibs"
           From libs.U:

           This variable should be non-empty if non-versioned shared  libraries
           (libfoo.so.x.y)  are  to  be  ignored (because they cannot be linked
           against).

       "inc_version_list"
           From inc_version_list.U:

           This variable specifies the list of  subdirectories  in  over  which
           perl.c:incpush()  and  lib/lib.pm  will  automatically  search  when
           adding  directories  to  @"INC".   The  elements  in  the  list  are
           separated by spaces.  This is only useful if you have a perl library
           directory  tree  structured like the default one.  See "INSTALL" for
           how this works.  The versioned site_perl directory was introduced in
           5.005, so that is the lowest possible value.

           This  list  includes  architecture-dependent  directories  back   to
           version   $api_versionstring   (e.g.   5.5.640)   and  architecture-
           independent directories all the way back to 5.005.

       "inc_version_list_init"
           From inc_version_list.U:

           This variable holds the same list as inc_version_list, but each item
           is enclosed in double quotes and separated by commas,  suitable  for
           use in the "PERL_INC_VERSION_LIST" initialization.

       "incpath"
           From usrinc.U:

           This  variable must precede the normal include path to get the right
           one, as in $incpath/usr/include or $incpath/usr/lib.  Value  can  be
           "" or /bsd43 on mips.

       "incpth"
           From libpth.U:

           This  variable must precede the normal include path to get the right
           one, as in $incpath/usr/include or $incpath/usr/lib.  Value  can  be
           "" or /bsd43 on mips.

       "inews"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "initialinstalllocation"
           From bin.U:

           When userelocatableinc is true, this  variable  holds  the  location
           that  make install should copy the perl binary to, with all the run-
           time relocatable paths calculated from this at install  time.   When
           used,  it  is  initialized to the original value of binexp, and then
           binexp is set to .../, as the other binaries are found  relative  to
           the perl binary.

       "installarchlib"
           From archlib.U:

           This  variable  is  really  the same as archlibexp but may differ on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installbin"
           From bin.U:

           This variable is the same as binexp unless "AFS" is running in which
           case the user is explicitly prompted for it.  This  variable  should
           always be used in your makefiles for maximum portability.

       "installhtml1dir"
           From html1dir.U:

           This  variable  is  really  the  same as html1direxp, unless you are
           using a different installprefix.  For extra portability, you  should
           only use this variable within your makefiles.

       "installhtml3dir"
           From html3dir.U:

           This  variable  is  really  the  same as html3direxp, unless you are
           using a different installprefix.  For extra portability, you  should
           only use this variable within your makefiles.

       "installman1dir"
           From man1dir.U:

           This variable is really the same as man1direxp, unless you are using
           "AFS"  in  which  case  it points to the read/write location whereas
           man1direxp only points to the read-only access location.  For  extra
           portability,   you   should  only  use  this  variable  within  your
           makefiles.

       "installman3dir"
           From man3dir.U:

           This variable is really the same as man3direxp, unless you are using
           "AFS" in which case it points to  the  read/write  location  whereas
           man3direxp  only  points to the read-only access location. For extra
           portability,  you  should  only  use  this  variable   within   your
           makefiles.

       "installprefix"
           From installprefix.U:

           This  variable  holds  the  name  of the directory below which "make
           install" will install the package.  For most users, this is the same
           as prefix.  However, it is useful for installing the software into a
           different (usually temporary) location after which it can be bundled
           up and moved somehow to the final location specified by prefix.

       "installprefixexp"
           From installprefix.U:

           This variable holds the full absolute path of installprefix with all
           ~-expansion done.

       "installprivlib"
           From privlib.U:

           This variable is really the same as privlibexp  but  may  differ  on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installscript"
           From scriptdir.U:

           This variable is usually the same as scriptdirexp, unless you are on
           a  system running "AFS", in which case they may differ slightly. You
           should  always  use  this  variable  within   your   makefiles   for
           portability.

       "installsitearch"
           From sitearch.U:

           This  variable  is  really the same as sitearchexp but may differ on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installsitebin"
           From sitebin.U:

           This variable is usually the same as sitebinexp, unless you are on a
           system running "AFS", in which case they may  differ  slightly.  You
           should   always   use   this  variable  within  your  makefiles  for
           portability.

       "installsitehtml1dir"
           From sitehtml1dir.U:

           This variable is really the same as sitehtml1direxp, unless you  are
           using  "AFS"  in  which  case  it  points to the read/write location
           whereas html1direxp only points to the  read-only  access  location.
           For extra portability, you should only use this variable within your
           makefiles.

       "installsitehtml3dir"
           From sitehtml3dir.U:

           This  variable is really the same as sitehtml3direxp, unless you are
           using "AFS" in which case  it  points  to  the  read/write  location
           whereas  html3direxp  only  points to the read-only access location.
           For extra portability, you should only use this variable within your
           makefiles.

       "installsitelib"
           From sitelib.U:

           This variable is really the same as sitelibexp  but  may  differ  on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installsiteman1dir"
           From siteman1dir.U:

           This  variable  is really the same as siteman1direxp, unless you are
           using "AFS" in which case  it  points  to  the  read/write  location
           whereas man1direxp only points to the read-only access location. For
           extra  portability,  you  should  only use this variable within your
           makefiles.

       "installsiteman3dir"
           From siteman3dir.U:

           This variable is really the same as siteman3direxp, unless  you  are
           using  "AFS"  in  which  case  it  points to the read/write location
           whereas man3direxp only points to the read-only access location. For
           extra portability, you should only use  this  variable  within  your
           makefiles.

       "installsitescript"
           From sitescript.U:

           This  variable  is usually the same as sitescriptexp, unless you are
           on a system running "AFS", in which case they may  differ  slightly.
           You  should  always  use  this  variable  within  your makefiles for
           portability.

       "installstyle"
           From installstyle.U:

           This variable describes the "style" of the perl installation.   This
           is  intended  to  be useful for tools that need to manipulate entire
           perl distributions.  Perl  itself  doesn't  use  this  to  find  its
           libraries   --  the  library  directories  are  stored  directly  in
           Config.pm.   Currently,  there  are  only  two  styles:   "lib"  and
           lib/perl5.   The  default  library locations (e.g. privlib, sitelib)
           are either $prefix/lib or $prefix/lib/perl5.  The former  is  useful
           if  $prefix is a directory dedicated to perl (e.g. /opt/perl), while
           the latter is useful if $prefix is shared by many packages, e.g.  if
           $prefix=/usr/local.

           Unfortunately,  while  this "style" variable is used to set defaults
           for all three directory hierarchies (core, vendor, and site),  there
           is  no guarantee that the same style is actually appropriate for all
           those directories.  For example, $prefix  might  be  /opt/perl,  but
           $siteprefix might be /usr/local.  (Perhaps, in retrospect, the "lib"
           style  should never have been supported, but it did seem like a nice
           idea at the time.)

           The situation is even less clear for tools such  as  MakeMaker  that
           can  be used to install additional modules into non-standard places.
           For example, if a user intends to install a module  into  a  private
           directory  (perhaps  by  setting "PREFIX" on the Makefile.PL command
           line), then there is no reason to  assume  that  the  Configure-time
           $installstyle setting will be relevant for that "PREFIX".

           This  may  later  be  extended  to  include other information, so be
           careful with pattern-matching on the results.

           For compatibility with perl5.005 and earlier, the default setting is
           based on whether or not $prefix contains the string "perl".

       "installusrbinperl"
           From instubperl.U:

           This variable  tells  whether  Perl  should  be  installed  also  as
           /usr/bin/perl in addition to $installbin/perl

       "installvendorarch"
           From vendorarch.U:

           This  variable is really the same as vendorarchexp but may differ on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installvendorbin"
           From vendorbin.U:

           This variable is really the same as vendorbinexp but may  differ  on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installvendorhtml1dir"
           From vendorhtml1dir.U:

           This variable is really the same as vendorhtml1direxp but may differ
           on  those  systems  using  "AFS".  For  extra portability, only this
           variable should be used in makefiles.

       "installvendorhtml3dir"
           From vendorhtml3dir.U:

           This variable is really the same as vendorhtml3direxp but may differ
           on those systems using  "AFS".  For  extra  portability,  only  this
           variable should be used in makefiles.

       "installvendorlib"
           From vendorlib.U:

           This  variable  is really the same as vendorlibexp but may differ on
           those systems using "AFS". For extra portability, only this variable
           should be used in makefiles.

       "installvendorman1dir"
           From vendorman1dir.U:

           This variable is really the same as vendorman1direxp but may  differ
           on  those  systems  using  "AFS".  For  extra portability, only this
           variable should be used in makefiles.

       "installvendorman3dir"
           From vendorman3dir.U:

           This variable is really the same as vendorman3direxp but may  differ
           on  those  systems  using  "AFS".  For  extra portability, only this
           variable should be used in makefiles.

       "installvendorscript"
           From vendorscript.U:

           This variable is really the same as vendorscriptexp but  may  differ
           on  those  systems  using  "AFS".  For  extra portability, only this
           variable should be used in makefiles.

       "intsize"
           From intsize.U:

           This variable contains the value  of  the  "INTSIZE"  symbol,  which
           indicates to the C program how many bytes there are in an int.

       "issymlink"
           From issymlink.U:

           This variable holds the test command to test for a symbolic link (if
           they  are  supported).   Typical  values include "test -h" and "test
           -L".

       "ivdformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "IV" as a signed decimal integer.

       "ivsize"
           From perlxv.U:

           This variable is the size of an "IV" in bytes.

       "ivtype"
           From perlxv.U:

           This variable contains the C type used for Perl's "IV".

   k
       "known_extensions"
           From Extensions.U:

           This  variable holds a list of all extensions (both "XS" and non-xs)
           included in the package source distribution.   This  information  is
           only  really  of  use  during  the  Perl build, as the list makes no
           distinction between extensions which were build and  installed,  and
           those  which where not.  See "extensions" for the list of extensions
           actually built and available.

       "ksh"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

   l
       "ld"
           From dlsrc.U:

           This variable indicates the program to be used to link libraries for
           dynamic loading.  On some systems, it is "ld".  On "ELF" systems, it
           should be $cc.  Mostly, we'll try to respect the hint file setting.

       "ld_can_script"
           From dlsrc.U:

           This  variable  shows  if  the loader accepts scripts in the form of
           -Wl,--version-script=ld.script. This is currently only supported for
           "GNU" ld on "ELF" in dynamic loading builds.

       "lddlflags"
           From dlsrc.U:

           This variable contains any special  flags  that  might  need  to  be
           passed  to  $ld  to  create  a  shared  library suitable for dynamic
           loading.  It is up to the makefile to use it.  For hpux,  it  should
           be "-b".  For sunos 4.1, it is empty.

       "ldflags"
           From ccflags.U:

           This  variable contains any additional C loader flags desired by the
           user.  It is up to the Makefile to use this.

       "ldflags_uselargefiles"
           From uselfs.U:

           This variable contains the loader flags needed by large file  builds
           and added to ldflags by hints files.

       "ldlibpthname"
           From libperl.U:

           This  variable  holds  the  name  of the shared library search path,
           often "LD_LIBRARY_PATH".  To get an empty  string,  the  hints  file
           must set this to "none".

       "less"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the less program.  After  Configure  runs,  the
           value is reset to a plain "less" and is not useful.

       "lib_ext"
           From Unix.U:

           This is an old synonym for _a.

       "libc"
           From libc.U:

           This variable contains the location of the C library.

       "libperl"
           From libperl.U:

           The  perl executable is obtained by linking perlmain.c with libperl,
           any static extensions  (usually  just  DynaLoader),  and  any  other
           libraries  needed on this system.  libperl is usually libperl.a, but
           can also be libperl.so.xxx if  the  user  wishes  to  build  a  perl
           executable with a shared library.

       "libpth"
           From libpth.U:

           This  variable holds the general path (space-separated) used to find
           libraries. It is intended to be used by other units.

       "libs"
           From libs.U:

           This variable holds the additional libraries we want to use.  It  is
           up to the Makefile to deal with it.  The list can be empty.

       "libsdirs"
           From libs.U:

           This  variable  holds  the  directory  names  aka  dirnames  of  the
           libraries we found and accepted, duplicates are removed.

       "libsfiles"
           From libs.U:

           This variable holds the filenames aka basenames of the libraries  we
           found and accepted.

       "libsfound"
           From libs.U:

           This variable holds the full pathnames of the libraries we found and
           accepted.

       "libspath"
           From libs.U:

           This variable holds the directory names probed for libraries.

       "libswanted"
           From Myinit.U:

           This  variable  holds a list of all the libraries we want to search.
           The order is chosen to pick up the c library ahead  of  ucb  or  bsd
           libraries for SVR4.

       "libswanted_uselargefiles"
           From uselfs.U:

           This variable contains the libraries needed by large file builds and
           added  to  ldflags  by hints files.  It is a space separated list of
           the library names without the "lib" prefix or any suffix, just  like
           libswanted..

       "line"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "lint"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "lkflags"
           From ccflags.U:

           This variable contains any additional C partial linker flags desired
           by the user.  It is up to the Makefile to use this.

       "ln"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the ln  program.   After  Configure  runs,  the
           value is reset to a plain "ln" and is not useful.

       "lns"
           From lns.U:

           This  variable  holds the name of the command to make symbolic links
           (if they are supported).  It can be used  in  the  Makefile.  It  is
           either "ln -s" or "ln"

       "localtime_r_proto"
           From d_localtime_r.U:

           This  variable  encodes the prototype of localtime_r.  It is zero if
           d_localtime_r is  undef,  and  one  of  the  "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_localtime_r is defined.

       "locincpth"
           From ccflags.U:

           This  variable  contains  a  list  of  additional  directories to be
           searched by the compiler.  The appropriate "-I" directives  will  be
           added  to  ccflags.   This  is  intended  to  simplify setting local
           directories from the Configure command line.  It's not much, but  it
           parallels the loclibpth stuff in libpth.U.

       "loclibpth"
           From libpth.U:

           This  variable  holds the paths (space-separated) used to find local
           libraries.  It is prepended to libpth, and is intended to be  easily
           set from the command line.

       "longdblinfbytes"
           From infnan.U:

           This variable contains comma-separated list of hexadecimal bytes for
           the long double precision infinity.

       "longdblkind"
           From d_longdbl.U:

           This  variable,  if  defined, encodes the type of a long double: 0 =
           double, 1 = "IEEE" 754 128-bit little endian, 2 = "IEEE" 754 128-bit
           big endian, 3 = x86 80-bit little endian, 4 = x86 80-bit big endian,
           5 = double-double 128-bit little endian, 6 =  double-double  128-bit
           big  endian,  7  = 128-bit mixed-endian double-double (64-bit LEs in
           "BE"), 8 = 128-bit mixed-endian double-double (64-bit BEs in  "LE"),
           9  =  128-bit  "PDP"-style  mixed-endian  long doubles, -1 = unknown
           format.

       "longdblmantbits"
           From mantbits.U:

           This symbol, if defined, tells how many mantissa bits there  are  in
           long  double precision floating point format.  Note that this can be
           "LDBL_MANT_DIG" minus one, since  "LDBL_MANT_DIG"  can  include  the
           "IEEE"  754  implicit  bit.  The common x86-style 80-bit long double
           does not have an implicit bit.

       "longdblnanbytes"
           From infnan.U:

           This variable contains comma-separated list of hexadecimal bytes for
           the long double precision not-a-number.

       "longdblsize"
           From d_longdbl.U:

           This variable contains the value of  the  "LONG_DOUBLESIZE"  symbol,
           which  indicates to the C program how many bytes there are in a long
           double, if this system supports long doubles.   Note  that  this  is
           sizeof(long double), which may include unused bytes.

       "longlongsize"
           From d_longlong.U:

           This variable contains the value of the "LONGLONGSIZE" symbol, which
           indicates  to the C program how many bytes there are in a long long,
           if this system supports long long.

       "longsize"
           From intsize.U:

           This variable contains the value of  the  "LONGSIZE"  symbol,  which
           indicates to the C program how many bytes there are in a long.

       "lp"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "lpr"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "ls"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the ls  program.   After  Configure  runs,  the
           value is reset to a plain "ls" and is not useful.

       "lseeksize"
           From lseektype.U:

           This variable defines lseektype to be something like off_t, long, or
           whatever  type  is used to declare lseek offset's type in the kernel
           (which also appears to be lseek's return type).

       "lseektype"
           From lseektype.U:

           This variable defines lseektype to be something like off_t, long, or
           whatever type is used to declare lseek offset's type in  the  kernel
           (which also appears to be lseek's return type).

   m
       "mail"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "mailx"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "make"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the make program.  After  Configure  runs,  the
           value is reset to a plain "make" and is not useful.

       "make_set_make"
           From make.U:

           Some  versions  of  "make"  set the variable "MAKE".  Others do not.
           This variable contains the string to be included in  Makefile.SH  so
           that  "MAKE"  is  set  if  needed,  and not if not needed.  Possible
           values are:

           make_set_make="#"        # If your make  program  handles  this  for
           you,

           make_set_make="MAKE=$make"    # if it doesn't.

           This  uses  a  comment  character so that we can distinguish a "set"
           value (from a previous config.sh or Configure "-D" option)  from  an
           uncomputed value.

       "mallocobj"
           From mallocsrc.U:

           This  variable  contains  the name of the malloc.o that this package
           generates, if that malloc.o is preferred  over  the  system  malloc.
           Otherwise  the  value  is  null.   This  variable  is  intended  for
           generating Makefiles.  See mallocsrc.

       "mallocsrc"
           From mallocsrc.U:

           This variable contains the name of the malloc.c that comes with  the
           package,  if  that  malloc.c  is  preferred  over the system malloc.
           Otherwise  the  value  is  null.   This  variable  is  intended  for
           generating Makefiles.

       "malloctype"
           From mallocsrc.U:

           This  variable  contains  the  kind  of  ptr  returned by malloc and
           realloc.

       "man1dir"
           From man1dir.U:

           This variable contains the name of the  directory  in  which  manual
           source  pages  are  to  be  put.   It  is  the responsibility of the
           Makefile.SH to get the value of this into the proper  command.   You
           must be prepared to do the ~name expansion yourself.

       "man1direxp"
           From man1dir.U:

           This  variable  is the same as the man1dir variable, but is filename
           expanded at configuration time, for convenient use in makefiles.

       "man1ext"
           From man1dir.U:

           This variable contains the extension that  the  manual  page  should
           have:  one  of "n", "l", or 1.  The Makefile must supply the ..  See
           man1dir.

       "man3dir"
           From man3dir.U:

           This variable contains the name of the  directory  in  which  manual
           source  pages  are  to  be  put.   It  is  the responsibility of the
           Makefile.SH to get the value of this into the proper  command.   You
           must be prepared to do the ~name expansion yourself.

       "man3direxp"
           From man3dir.U:

           This  variable  is the same as the man3dir variable, but is filename
           expanded at configuration time, for convenient use in makefiles.

       "man3ext"
           From man3dir.U:

           This variable contains the extension that  the  manual  page  should
           have:  one  of "n", "l", or 3.  The Makefile must supply the ..  See
           man3dir.

       "mips_type"
           From usrinc.U:

           This variable holds  the  environment  type  for  the  mips  system.
           Possible values are "BSD 4.3" and "System V".

       "mistrustnm"
           From Csym.U:

           This  variable  can be used to establish a fallthrough for the cases
           where nm fails to find a symbol.  If usenm is false or usenm is true
           and mistrustnm is false, this variable has no effect.  If  usenm  is
           true and mistrustnm is "compile", a test program will be compiled to
           try  to  find  any  symbol  that can't be located via nm lookup.  If
           mistrustnm is "run", the test program will be run as well  as  being
           compiled.

       "mkdir"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the mkdir program.  After Configure  runs,  the
           value is reset to a plain "mkdir" and is not useful.

       "mmaptype"
           From d_mmap.U:

           This  symbol  contains  the  type of pointer returned by mmap() (and
           simultaneously the type of the first argument).  It can be "void  *"
           or "caddr_t".

       "modetype"
           From modetype.U:

           This  variable  defines  modetype  to be something like mode_t, int,
           unsigned short, or whatever type is used to declare file  modes  for
           system calls.

       "more"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the more program.  After  Configure  runs,  the
           value is reset to a plain "more" and is not useful.

       "multiarch"
           From multiarch.U:

           This  variable  conditionally  defines  the "MULTIARCH" symbol which
           signifies the presence of multiplatform files.  This is normally set
           by hints files.

       "mv"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "myarchname"
           From archname.U:

           This variable holds the architecture name computed by Configure in a
           previous  run.  It  is  not  intended  to be perused by any user and
           should never be set in a hint file.

       "mydomain"
           From myhostname.U:

           This variable contains the eventual value of the "MYDOMAIN"  symbol,
           which is the domain of the host the program is going to run on.  The
           domain  must be appended to myhostname to form a complete host name.
           The dot comes with  mydomain,  and  need  not  be  supplied  by  the
           program.

       "myhostname"
           From myhostname.U:

           This  variable  contains  the  eventual  value  of  the "MYHOSTNAME"
           symbol, which is the name of the host the program is  going  to  run
           on.   The  domain is not kept with hostname, but must be gotten from
           mydomain.  The dot comes with mydomain, and need not be supplied  by
           the program.

       "myuname"
           From Oldconfig.U:

           The  output of "uname -a" if available, otherwise the hostname.  The
           whole thing is then lower-cased and slashes and  single  quotes  are
           removed.

   n
       "n" From n.U:

           This variable contains the "-n" flag if that is what causes the echo
           command  to  suppress newline.  Otherwise it is null.  Correct usage
           is $echo $n "prompt for a question: $c".

       "need_va_copy"
           From need_va_copy.U:

           This symbol, if  defined,  indicates  that  the  system  stores  the
           variable argument list datatype, va_list, in a format that cannot be
           copied  by  simple assignment, so that some other means must be used
           when copying is required.  As such systems vary in  their  provision
           (or   non-provision)   of  copying  mechanisms,  handy.h  defines  a
           platform- "independent" macro, Perl_va_copy(src,  dst),  to  do  the
           job.

       "netdb_hlen_type"
           From netdbtype.U:

           This   variable  holds  the  type  used  for  the  2nd  argument  to
           gethostbyaddr().  Usually, this is int or size_t or unsigned.   This
           is only useful if you have gethostbyaddr(), naturally.

       "netdb_host_type"
           From netdbtype.U:

           This   variable  holds  the  type  used  for  the  1st  argument  to
           gethostbyaddr().  Usually, this is char * or void *,  possibly  with
           or  without  a  const  prefix.   This  is  only  useful  if you have
           gethostbyaddr(), naturally.

       "netdb_name_type"
           From netdbtype.U:

           This  variable  holds  the   type   used   for   the   argument   to
           gethostbyname().   Usually, this is char * or const char *.  This is
           only useful if you have gethostbyname(), naturally.

       "netdb_net_type"
           From netdbtype.U:

           This  variable  holds  the  type  used  for  the  1st  argument   to
           getnetbyaddr().   Usually, this is int or long.  This is only useful
           if you have getnetbyaddr(), naturally.

       "nm"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the  nm program.  After Configure runs, the
           value is reset to a plain "nm" and is not useful.

       "nm_opt"
           From usenm.U:

           This variable holds the options that may be necessary for nm.

       "nm_so_opt"
           From usenm.U:

           This variable holds the options that may be necessary for nm to work
           on a shared library but that can not be used on an archive  library.
           Currently,  this  is  only  used  by  Linux,  where  nm --dynamic is
           *required* to get symbols from  an  "ELF"  library  which  has  been
           stripped,  but nm --dynamic is *fatal* on an archive library.  Maybe
           Linux should just always set usenm=false.

       "nonxs_ext"
           From Extensions.U:

           This variable holds a  list  of  all  non-xs  extensions  built  and
           installed  by  the  package.   By  default,  all  non-xs  extensions
           distributed will be built, with the exception  of  platform-specific
           extensions (currently only one "VMS" specific extension).

       "nroff"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the nroff program.  After Configure  runs,  the
           value is reset to a plain "nroff" and is not useful.

       "nvEUformat"
           From perlxvf.U:

           This  variable  contains  the format string used for printing a Perl
           "NV" using %E-ish floating point format.

       "nvFUformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "NV" using %F-ish floating point format.

       "nvGUformat"
           From perlxvf.U:

           This  variable  contains  the format string used for printing a Perl
           "NV" using %G-ish floating point format.

       "nv_overflows_integers_at"
           From perlxv.U:

           This variable gives the largest integer value that NVs can hold as a
           constant floating point expression.  If it could not be  determined,
           it holds the value 0.

       "nv_preserves_uv_bits"
           From perlxv.U:

           This  variable  indicates  how  many  of bits type uvtype a variable
           nvtype can preserve.

       "nveformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "NV" using %e-ish floating point format.

       "nvfformat"
           From perlxvf.U:

           This  variable  contains  the format string used for printing a Perl
           "NV" using %f-ish floating point format.

       "nvgformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "NV" using %g-ish floating point format.

       "nvmantbits"
           From mantbits.U:

           This  variable  tells how many bits the mantissa of a Perl "NV" has,
           not including the possible implicit bit.

       "nvsize"
           From perlxv.U:

           This variable is the size of a Perl "NV" in bytes.  Note  that  some
           floating point formats have unused bytes.

       "nvtype"
           From perlxv.U:

           This variable contains the C type used for Perl's "NV".

   o
       "o_nonblock"
           From nblock_io.U:

           This  variable  bears  the  symbol value to be used during open() or
           fcntl() to turn on non-blocking I/O for a file  descriptor.  If  you
           wish  to  switch  between  blocking  and  non-blocking,  you may try
           ioctl("FIOSNBIO") instead,  but  that  is  only  supported  by  some
           devices.

       "obj_ext"
           From Unix.U:

           This is an old synonym for _o.

       "old_pthread_create_joinable"
           From d_pthrattrj.U:

           This variable defines the constant to use for creating joinable (aka
           undetached)     pthreads.      Unused     if    pthread.h    defines
           "PTHREAD_CREATE_JOINABLE".    If   used,   possible    values    are
           "PTHREAD_CREATE_UNDETACHED" and "__UNDETACHED".

       "optimize"
           From ccflags.U:

           This  variable  contains  any optimizer/debugger flag that should be
           used.  It is up to the Makefile to use it.

       "orderlib"
           From orderlib.U:

           This variable is "true" if  the  components  of  libraries  must  be
           ordered  (with  `lorder  $*  |  tsort`)  before  placing  them in an
           archive.  Set to  "false"  if  ranlib  or  ar  can  generate  random
           libraries.

       "osname"
           From Oldconfig.U:

           This  variable  contains  the  operating  system  name  (e.g. sunos,
           solaris, hpux, etc.).   It  can  be  useful  later  on  for  setting
           defaults.  Any spaces are replaced with underscores.  It is set to a
           null string if we can't figure it out.

       "osvers"
           From Oldconfig.U:

           This  variable  contains  the operating system version (e.g.  4.1.3,
           5.2, etc.).  It is primarily used for helping select an  appropriate
           hints  file, but might be useful elsewhere for setting defaults.  It
           is set to '' if we can't figure it out.  We try to be flexible about
           how much of the version number to keep, e.g. if  4.1.1,  4.1.2,  and
           4.1.3  are  essentially the same for this package, hints files might
           just be os_4.0 or os_4.1, etc., not keeping separate files for  each
           little release.

       "otherlibdirs"
           From otherlibdirs.U:

           This  variable  contains a colon-separated set of paths for the perl
           binary to search for additional library  files  or  modules.   These
           directories  will  be  tacked  to  the  end  of  @"INC".   Perl will
           automatically search below each path for version- and  architecture-
           specific  directories.   See  inc_version_list  for more details.  A
           value of " " means "none" and is used to preserve this value for the
           next run through Configure.

   p
       "package"
           From package.U:

           This variable contains the name of the  package  being  constructed.
           It is primarily intended for the use of later Configure units.

       "pager"
           From pager.U:

           This  variable  contains  the  name  of  the  preferred pager on the
           system.  Usual values are (the full pathnames of) more, less, pg, or
           cat.

       "passcat"
           From nis.U:

           This variable contains a command  that  produces  the  text  of  the
           /etc/passwd  file.   This  is normally "cat /etc/passwd", but can be
           "ypcat passwd" when "NIS" is used.  On some systems, such as  os390,
           there  may  be no equivalent command, in which case this variable is
           unset.

       "patchlevel"
           From patchlevel.U:

           The patchlevel level of this package.  The value of patchlevel comes
           from the patchlevel.h file.  In a version number such as 5.6.1, this
           is the 6.  In patchlevel.h, this is referred to as "PERL_VERSION".

       "path_sep"
           From Unix.U:

           This is an old synonym for p_  in  Head.U,  the  character  used  to
           separate elements in the command shell search "PATH".

       "perl"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the perl program.  After  Configure  runs,  the
           value is reset to a plain "perl" and is not useful.

       "perl5"
           From perl5.U:

           This  variable  contains  the  full  path  (if  any) to a previously
           installed perl5.005 or later suitable  for  running  the  script  to
           determine inc_version_list.

       "perl_lc_all_category_positions_init"
           From disparate_lc_all.U:

           This  symbol,  when  defined,  gives  the C initializer for an array
           whose element [0] is the first category in the  string  returned  by
           setlocale("LC_ALL", "NULL") when not all categories are the same, on
           systems  that  use  a  positional  notation.   After  element [0] is
           $lc_all_separator_init, then the category given by element [1],  and
           so on.

       "perl_lc_all_separator"
           From disparate_lc_all.U:

           This  symbol,  when  defined,  gives  the substring used to separate
           categories in the aggregated string returned by  setlocale("LC_ALL",
           "NULL") when not all categories are in the same locale.  This is for
           systems  that  use  a positional notation as opposed to "name=value"
           pairs.

       "perl_patchlevel"
           From patchlevel.U:

           This is the Perl  patch  level,  a  numeric  change  identifier,  as
           defined  by  whichever  source  code  maintenance  system is used to
           maintain the patches; currently Perforce.   It  does  not  correlate
           with  the Perl version numbers or the maintenance versus development
           dichotomy except by also being increasing.

       "perl_static_inline"
           From d_static_inline.U:

           This variable defines the "PERL_STATIC_INLINE" symbol to  the  best-
           guess incantation to use for static inline functions.  Possibilities
           include  static  inline        (c99) static __inline__   (gcc -ansi)
           static __inline      ("MSVC")  static  _inline       (older  "MSVC")
           static              (c89 compilers)

       "perl_thread_local"
           From d_thread_local.U:

           This  variable  gives  the  value for the "PERL_THREAD_LOCAL" symbol
           (when defined), which gives a linkage specification for thread-local
           storage.

       "perladmin"
           From perladmin.U:

           Electronic mail address of the perl5 administrator.

       "perllibs"
           From End.U:

           The list of libraries needed by Perl only (any libraries  needed  by
           extensions only will by dropped, if using dynamic loading).

       "perlpath"
           From perlpath.U:

           This  variable contains the eventual value of the "PERLPATH" symbol,
           which contains the name of the perl interpreter to be used in  shell
           scripts  and  in  the  "eval  "exec""  idiom.   This variable is not
           necessarily  the  pathname  of  the   file   containing   the   perl
           interpreter;  you  must append the executable extension (_exe) if it
           is not already present.  Note that Perl code that  runs  during  the
           Perl  build  process cannot reference this variable, as Perl may not
           have been installed, or  even  if  installed,  may  be  a  different
           version of Perl.

       "pg"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the pg  program.   After  Configure  runs,  the
           value is reset to a plain "pg" and is not useful.

       "phostname"
           From myhostname.U:

           This variable contains the eventual value of the "PHOSTNAME" symbol,
           which  is a command that can be fed to popen() to get the host name.
           The program should probably not presume that the domain is or  isn't
           there already.

       "pidtype"
           From pidtype.U:

           This  variable  defines  "PIDTYPE"  to be something like pid_t, int,
           ushort, or whatever type is used  to  declare  process  ids  in  the
           kernel.

       "plibpth"
           From libpth.U:

           Holds  the private path used by Configure to find out the libraries.
           Its value is prepend to libpth. This variable takes care of  special
           machines, like the mips.  Usually, it should be empty.

       "pmake"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "pr"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "prefix"
           From prefix.U:

           This  variable  holds the name of the directory below which the user
           will  install  the  package.   Usually,  this  is  /usr/local,   and
           executables  go  in /usr/local/bin, library stuff in /usr/local/lib,
           man pages in /usr/local/man, etc.  It is only used to  set  defaults
           for things in bin.U, mansrc.U, privlib.U, or scriptdir.U.

       "prefixexp"
           From prefix.U:

           This  variable  holds  the full absolute path of the directory below
           which the user will install the package.  Derived from prefix.

       "privlib"
           From privlib.U:

           This variable contains the eventual value of the  "PRIVLIB"  symbol,
           which  is  the name of the private library for this package.  It may
           have a ~ on the front. It is up to the makefile to eventually create
           this directory while performing installation (with ~ substitution).

       "privlibexp"
           From privlib.U:

           This variable is the ~name expanded version of privlib, so that  you
           may use it directly in Makefiles or shell scripts.

       "procselfexe"
           From d_procselfexe.U:

           If  d_procselfexe  is  defined,  $procselfexe is the filename of the
           symbolic link pointing to the absolute  pathname  of  the  executing
           program.

       "ptrsize"
           From ptrsize.U:

           This  variable  contains  the  value  of the "PTRSIZE" symbol, which
           indicates to the C program how many bytes there are in a pointer.

   q
       "quadkind"
           From quadtype.U:

           This variable, if defined, encodes the type of a quad: 1 = int, 2  =
           long, 3 = long long, 4 = int64_t.

       "quadtype"
           From quadtype.U:

           This  variable  defines  Quad_t to be something like long, int, long
           long, int64_t, or whatever type is used for 64-bit integers.

   r
       "randbits"
           From randfunc.U:

           Indicates how many  bits  are  produced  by  the  function  used  to
           generate normalized random numbers.

       "randfunc"
           From randfunc.U:

           Indicates  the  name  of  the random number function to use.  Values
           include drand48, random, and rand.  In  C  programs,  the  "Drand01"
           macro  is  defined  to generate uniformly distributed random numbers
           over the range [0., 1.[ (see drand01 and nrand).

       "random_r_proto"
           From d_random_r.U:

           This variable encodes the prototype of  random_r.   It  is  zero  if
           d_random_r  is  undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_random_r is defined.

       "randseedtype"
           From randfunc.U:

           Indicates the type of the argument of the seedfunc.

       "ranlib"
           From orderlib.U:

           This variable is set to the pathname of the ranlib program, if it is
           needed to generate random libraries.  Set to ":" if ar can  generate
           random libraries or if random libraries are not supported

       "rd_nodata"
           From nblock_io.U:

           This  variable  holds  the  return  code from read() when no data is
           present. It should be -1, but some systems return 0 when  "O_NDELAY"
           is  used,  which  is  a shame because you cannot make the difference
           between no data and an EOF.. Sigh!

       "readdir64_r_proto"
           From d_readdir64_r.U:

           This variable encodes the prototype of readdir64_r.  It is  zero  if
           d_readdir64_r  is  undef,  and  one  of  the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_readdir64_r is defined.

       "readdir_r_proto"
           From d_readdir_r.U:

           This variable encodes the prototype of readdir_r.   It  is  zero  if
           d_readdir_r  is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_readdir_r is defined.

       "revision"
           From patchlevel.U:

           The value of revision  comes  from  the  patchlevel.h  file.   In  a
           version  number such as 5.6.1, this is the 5.  In patchlevel.h, this
           is referred to as "PERL_REVISION".

       "rm"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the  rm program.  After Configure runs, the
           value is reset to a plain "rm" and is not useful.

       "rm_try"
           From Unix.U:

           This  is  a  cleanup  variable  for  try  test  programs.   Internal
           Configure use only.

       "rmail"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "run"
           From Cross.U:

           This variable contains the command used by  Configure  to  copy  and
           execute  a cross-compiled executable in the target host.  Useful and
           available only during Perl build.  Empty string  ''  if  not  cross-
           compiling.

       "runnm"
           From usenm.U:

           This  variable  contains  "true" or "false" depending whether the nm
           extraction should be performed or not, according  to  the  value  of
           usenm and the flags on the Configure command line.

   s
       "sGMTIME_max"
           From time_size.U:

           This  variable  defines  the maximum value of the time_t offset that
           the system function gmtime () accepts

       "sGMTIME_min"
           From time_size.U:

           This variable defines the minimum value of the  time_t  offset  that
           the system function gmtime () accepts

       "sLOCALTIME_max"
           From time_size.U:

           This  variable  defines  the maximum value of the time_t offset that
           the system function localtime () accepts

       "sLOCALTIME_min"
           From time_size.U:

           This variable defines the minimum value of the  time_t  offset  that
           the system function localtime () accepts

       "sPRIEUldbl"
           From longdblfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format long doubles (format "E") for output.  The "U" in the name is
           to separate this from sPRIeldbl so that even case-blind systems  can
           see the difference.

       "sPRIFUldbl"
           From longdblfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format long doubles (format "F") for output.  The "U" in the name is
           to separate this from sPRIfldbl so that even case-blind systems  can
           see the difference.

       "sPRIGUldbl"
           From longdblfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format long doubles (format "G") for output.  The "U" in the name is
           to separate this from sPRIgldbl so that even case-blind systems  can
           see the difference.

       "sPRIXU64"
           From quadfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format 64-bit hExADECimAl numbers (format "X") for output.  The  "U"
           in the name is to separate this from sPRIx64 so that even case-blind
           systems can see the difference.

       "sPRId64"
           From quadfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format 64-bit decimal numbers (format "d") for output.

       "sPRIeldbl"
           From longdblfio.U:

           This variable, if defined, contains the  string  used  by  stdio  to
           format long doubles (format "e") for output.

       "sPRIfldbl"
           From longdblfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format long doubles (format "f") for output.

       "sPRIgldbl"
           From longdblfio.U:

           This variable, if defined, contains the  string  used  by  stdio  to
           format long doubles (format "g") for output.

       "sPRIi64"
           From quadfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format 64-bit decimal numbers (format "i") for output.

       "sPRIo64"
           From quadfio.U:

           This variable, if defined, contains the  string  used  by  stdio  to
           format 64-bit octal numbers (format "o") for output.

       "sPRIu64"
           From quadfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format 64-bit unsigned decimal numbers (format "u") for output.

       "sPRIx64"
           From quadfio.U:

           This variable, if defined, contains the  string  used  by  stdio  to
           format 64-bit hexadecimal numbers (format "x") for output.

       "sSCNfldbl"
           From longdblfio.U:

           This  variable,  if  defined,  contains  the string used by stdio to
           format long doubles (format "f") for input.

       "sched_yield"
           From d_pthread_y.U:

           This variable defines the way to yield the execution of the  current
           thread.

       "scriptdir"
           From scriptdir.U:

           This  variable  holds  the  name  of the directory in which the user
           wants to put publicly scripts for the package in  question.   It  is
           either the same directory as for binaries, or a special one that can
           be mounted across different architectures, like /usr/share. Programs
           must be prepared to deal with ~name expansion.

       "scriptdirexp"
           From scriptdir.U:

           This  variable is the same as scriptdir, but is filename expanded at
           configuration time, for programs not wanting to bother with it.

       "sed"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of  the sed program.  After Configure runs, the
           value is reset to a plain "sed" and is not useful.

       "seedfunc"
           From randfunc.U:

           Indicates  the  random  number  generating  seed  function.   Values
           include srand48, srandom, and srand.

       "selectminbits"
           From selectminbits.U:

           This  variable  holds the minimum number of bits operated by select.
           That is, if you do select(n, ...), how many bits at  least  will  be
           cleared  in the masks if some activity is detected.  Usually this is
           either n or 32*ceil(n/32), especially  many  little-endians  do  the
           latter.  This is only useful if you have select(), naturally.

       "selecttype"
           From selecttype.U:

           This  variable  holds  the  type  used  for  the  2nd,  3rd, and 4th
           arguments to select.  Usually, this is "fd_set *",  if  "HAS_FD_SET"
           is  defined, and "int *" otherwise.  This is only useful if you have
           select(), naturally.

       "sendmail"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "setgrent_r_proto"
           From d_setgrent_r.U:

           This  variable  encodes  the prototype of setgrent_r.  It is zero if
           d_setgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_setgrent_r is defined.

       "sethostent_r_proto"
           From d_sethostent_r.U:

           This variable encodes the prototype of sethostent_r.  It is zero  if
           d_sethostent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_sethostent_r is defined.

       "setlocale_r_proto"
           From d_setlocale_r.U:

           This variable encodes the prototype of setlocale_r.  It is  zero  if
           d_setlocale_r  is  undef,  and  one  of  the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_setlocale_r is defined.

       "setnetent_r_proto"
           From d_setnetent_r.U:

           This variable encodes the prototype of setnetent_r.  It is  zero  if
           d_setnetent_r  is  undef,  and  one  of  the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_setnetent_r is defined.

       "setprotoent_r_proto"
           From d_setprotoent_r.U:

           This variable encodes the prototype of setprotoent_r.  It is zero if
           d_setprotoent_r is undef, and  one  of  the  "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_setprotoent_r is defined.

       "setpwent_r_proto"
           From d_setpwent_r.U:

           This  variable  encodes  the prototype of setpwent_r.  It is zero if
           d_setpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_setpwent_r is defined.

       "setservent_r_proto"
           From d_setservent_r.U:

           This variable encodes the prototype of setservent_r.  It is zero  if
           d_setservent_r  is  undef,  and  one  of the "REENTRANT_PROTO_T_ABC"
           macros of reentr.h if d_setservent_r is defined.

       "sh"
           From sh.U:

           This variable contains the full pathname of the shell used  on  this
           system  to  execute  Bourne  shell  scripts.   Usually, this will be
           /bin/sh, though it's possible that some systems will have  /bin/ksh,
           /bin/pdksh,   /bin/ash,   /bin/bash,   or  even  something  such  as
           D:/bin/sh.exe.  This unit comes before Options.U, so you  can't  set
           sh  with  a  "-D" option, though you can override this (and startsh)
           with "-O -Dsh=/bin/whatever -Dstartsh=whatever"

       "shar"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "sharpbang"
           From spitshell.U:

           This  variable  contains  the string #! if this system supports that
           construct.

       "shmattype"
           From d_shmat.U:

           This symbol contains the type of pointer returned  by  shmat().   It
           can be "void *" or "char *".

       "shortsize"
           From intsize.U:

           This  variable  contains  the  value of the "SHORTSIZE" symbol which
           indicates to the C program how many bytes there are in a short.

       "shrpenv"
           From libperl.U:

           If the user builds a shared libperl.so, then we  need  to  tell  the
           "perl"  executable  where  it  will  be  able  to find the installed
           libperl.so.  One way to do this  on  some  systems  is  to  set  the
           environment variable "LD_RUN_PATH" to the directory that will be the
           final  location of the shared libperl.so.  The makefile can use this
           with something like $shrpenv $("CC")  -o  perl  perlmain.o  $libperl
           $libs         Typical         values         are        shrpenv="env
           "LD_RUN_PATH"=$archlibexp/"CORE"" or shrpenv='' See  the  main  perl
           Makefile.SH for actual working usage.

           Alternatively, we might be able to use a command line option such as
           -R  $archlibexp/"CORE"  (Solaris)  or  -Wl,-rpath $archlibexp/"CORE"
           (Linux).

       "shsharp"
           From spitshell.U:

           This variable tells further Configure  units  whether  your  sh  can
           handle # comments.

       "sig_count"
           From sig_name.U:

           This  variable  holds  a number larger than the largest valid signal
           number.  This is usually the same as the "NSIG" macro.

       "sig_name"
           From sig_name.U:

           This variable holds the signal names, space separated.  The  leading
           "SIG" in signal name is removed.  A "ZERO" is prepended to the list.
           This is currently not used, sig_name_init is used instead.

       "sig_name_init"
           From sig_name.U:

           This  variable holds the signal names, enclosed in double quotes and
           separated by commas, suitable for use in the  "SIG_NAME"  definition
           below.   A  "ZERO"  is  prepended  to  the  list,  and  the  list is
           terminated with a plain 0.  The leading "SIG"  in  signal  names  is
           removed. See sig_num.

       "sig_num"
           From sig_name.U:

           This variable holds the signal numbers, space separated. A "ZERO" is
           prepended  to the list (corresponding to the fake "SIGZERO").  Those
           numbers correspond to  the value of the signal listed  in  the  same
           place  within  the  sig_name  list.   This  is  currently  not used,
           sig_num_init is used instead.

       "sig_num_init"
           From sig_name.U:

           This variable holds the signal numbers, enclosed  in  double  quotes
           and   separated  by  commas,  suitable  for  use  in  the  "SIG_NUM"
           definition below.  A "ZERO" is prepended to the list, and  the  list
           is terminated with a plain 0.

       "sig_size"
           From sig_name.U:

           This  variable  contains  the number of elements of the sig_name and
           sig_num arrays.

       "signal_t"
           From d_voidsig.U:

           This variable holds the type of the signal handler (void or int).

       "sitearch"
           From sitearch.U:

           This variable contains the eventual value of the "SITEARCH"  symbol,
           which  is  the name of the private library for this package.  It may
           have a ~ on the front. It is up to the makefile to eventually create
           this directory while performing installation (with ~  substitution).
           The standard distribution will put nothing in this directory.  After
           perl   has  been  installed,  users  may  install  their  own  local
           architecture-dependent modules  in  this  directory  with  MakeMaker
           Makefile.PL or equivalent.  See "INSTALL" for details.

       "sitearchexp"
           From sitearch.U:

           This variable is the ~name expanded version of sitearch, so that you
           may use it directly in Makefiles or shell scripts.

       "sitebin"
           From sitebin.U:

           This  variable  holds  the  name  of the directory in which the user
           wants to put add-on publicly executable files  for  the  package  in
           question.    It   is   most   often   a   local  directory  such  as
           /usr/local/bin. Programs using this variable  must  be  prepared  to
           deal  with  ~name  substitution.  The standard distribution will put
           nothing in this directory.  After perl has been installed, users may
           install their own local executables in this directory with MakeMaker
           Makefile.PL or equivalent.  See "INSTALL" for details.

       "sitebinexp"
           From sitebin.U:

           This is the same as the sitebin variable, but is  filename  expanded
           at configuration time, for use in your makefiles.

       "sitehtml1dir"
           From sitehtml1dir.U:

           This  variable  contains  the  name  of the directory in which site-
           specific html source pages are to be put.  It is the  responsibility
           of the Makefile.SH to get the value of this into the proper command.
           You  must  be  prepared  to  do  the  ~name expansion yourself.  The
           standard distribution will put nothing  in  this  directory.   After
           perl  has  been  installed,  users  may install their own local html
           pages in this directory with MakeMaker  Makefile.PL  or  equivalent.
           See "INSTALL" for details.

       "sitehtml1direxp"
           From sitehtml1dir.U:

           This  variable  is  the  same  as  the sitehtml1dir variable, but is
           filename expanded at  configuration  time,  for  convenient  use  in
           makefiles.

       "sitehtml3dir"
           From sitehtml3dir.U:

           This  variable  contains  the  name  of the directory in which site-
           specific library html source  pages  are  to  be  put.   It  is  the
           responsibility  of the Makefile.SH to get the value of this into the
           proper command.  You must be prepared  to  do  the  ~name  expansion
           yourself.   The  standard  distribution  will  put  nothing  in this
           directory.  After perl has been installed, users may  install  their
           own  local  library  html  pages  in  this  directory with MakeMaker
           Makefile.PL or equivalent.  See "INSTALL" for details.

       "sitehtml3direxp"
           From sitehtml3dir.U:

           This variable is the same  as  the  sitehtml3dir  variable,  but  is
           filename  expanded  at  configuration  time,  for  convenient use in
           makefiles.

       "sitelib"
           From sitelib.U:

           This variable contains the eventual value of the  "SITELIB"  symbol,
           which  is  the name of the private library for this package.  It may
           have a ~ on the front. It is up to the makefile to eventually create
           this directory while performing installation (with ~  substitution).
           The standard distribution will put nothing in this directory.  After
           perl   has  been  installed,  users  may  install  their  own  local
           architecture-independent modules in this  directory  with  MakeMaker
           Makefile.PL or equivalent.  See "INSTALL" for details.

       "sitelib_stem"
           From sitelib.U:

           This  variable  is  $sitelibexp  with  any trailing version-specific
           component    removed.     The    elements    in     inc_version_list
           (inc_version_list.U)  can be tacked onto this variable to generate a
           list of directories to search.

       "sitelibexp"
           From sitelib.U:

           This variable is the ~name expanded version of sitelib, so that  you
           may use it directly in Makefiles or shell scripts.

       "siteman1dir"
           From siteman1dir.U:

           This  variable  contains  the  name  of the directory in which site-
           specific  manual  source  pages  are  to  be   put.    It   is   the
           responsibility  of the Makefile.SH to get the value of this into the
           proper command.  You must be prepared  to  do  the  ~name  expansion
           yourself.   The  standard  distribution  will  put  nothing  in this
           directory.  After perl has been installed, users may  install  their
           own local man1 pages in this directory with MakeMaker Makefile.PL or
           equivalent.  See "INSTALL" for details.

       "siteman1direxp"
           From siteman1dir.U:

           This  variable  is  the  same  as  the  siteman1dir variable, but is
           filename expanded at  configuration  time,  for  convenient  use  in
           makefiles.

       "siteman3dir"
           From siteman3dir.U:

           This  variable  contains  the  name  of the directory in which site-
           specific library man  source  pages  are  to  be  put.   It  is  the
           responsibility  of the Makefile.SH to get the value of this into the
           proper command.  You must be prepared  to  do  the  ~name  expansion
           yourself.   The  standard  distribution  will  put  nothing  in this
           directory.  After perl has been installed, users may  install  their
           own local man3 pages in this directory with MakeMaker Makefile.PL or
           equivalent.  See "INSTALL" for details.

       "siteman3direxp"
           From siteman3dir.U:

           This  variable  is  the  same  as  the  siteman3dir variable, but is
           filename expanded at  configuration  time,  for  convenient  use  in
           makefiles.

       "siteprefix"
           From siteprefix.U:

           This  variable  holds  the full absolute path of the directory below
           which the user will install  add-on  packages.   See  "INSTALL"  for
           usage and examples.

       "siteprefixexp"
           From siteprefix.U:

           This  variable  holds  the full absolute path of the directory below
           which  the  user  will  install  add-on  packages.    Derived   from
           siteprefix.

       "sitescript"
           From sitescript.U:

           This  variable  holds  the  name  of the directory in which the user
           wants to put add-on publicly executable files  for  the  package  in
           question.    It   is   most   often   a   local  directory  such  as
           /usr/local/bin. Programs using this variable  must  be  prepared  to
           deal  with  ~name  substitution.  The standard distribution will put
           nothing in this directory.  After perl has been installed, users may
           install their own local scripts in  this  directory  with  MakeMaker
           Makefile.PL or equivalent.  See "INSTALL" for details.

       "sitescriptexp"
           From sitescript.U:

           This  is  the  same  as  the  sitescript  variable,  but is filename
           expanded at configuration time, for use in your makefiles.

       "sizesize"
           From sizesize.U:

           This variable contains the size of a sizetype in bytes.

       "sizetype"
           From sizetype.U:

           This variable defines sizetype to be something like size_t, unsigned
           long, or whatever type is used  to  declare  length  parameters  for
           string functions.

       "sleep"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "smail"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "so"
           From so.U:

           This  variable holds the extension used to identify shared libraries
           (also known as shared objects) on the system. Usually set to "so".

       "sockethdr"
           From d_socket.U:

           This variable has any cpp "-I" flags needed for socket support.

       "socketlib"
           From d_socket.U:

           This variable has the names  of  any  libraries  needed  for  socket
           support.

       "socksizetype"
           From socksizetype.U:

           This  variable holds the type used for the size argument for various
           socket calls like accept.  Usual values include  socklen_t,  size_t,
           and int.

       "sort"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the sort program.  After  Configure  runs,  the
           value is reset to a plain "sort" and is not useful.

       "spackage"
           From package.U:

           This  variable  contains  the name of the package being constructed,
           with  the  first  letter  uppercased,  i.e.  suitable  for  starting
           sentences.

       "spitshell"
           From spitshell.U:

           This  variable contains the command necessary to spit out a runnable
           shell on this system.  It is  either  cat  or  a  grep  "-v"  for  #
           comments.

       "srand48_r_proto"
           From d_srand48_r.U:

           This  variable  encodes  the  prototype of srand48_r.  It is zero if
           d_srand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC"  macros
           of reentr.h if d_srand48_r is defined.

       "srandom_r_proto"
           From d_srandom_r.U:

           This  variable  encodes  the  prototype of srandom_r.  It is zero if
           d_srandom_r is undef, and one of the "REENTRANT_PROTO_T_ABC"  macros
           of reentr.h if d_srandom_r is defined.

       "src"
           From src.U:

           This  variable  holds  the  (possibly  relative) path of the package
           source.  It is up to the Makefile  to  use  this  variable  and  set
           "VPATH"  accordingly  to  find the sources remotely.  Use $pkgsrc to
           have an absolute path.

       "ssizetype"
           From ssizetype.U:

           This variable defines ssizetype to be something like  ssize_t,  long
           or  int.  It is used by functions that return a count of bytes or an
           error condition.  It must be a signed type.  We  will  pick  a  type
           such that sizeof(SSize_t) == sizeof(Size_t).

       "st_dev_sign"
           From st_dev_def.U:

           This  variable  contains  the signedness of struct stat's st_dev.  1
           for unsigned, -1 for signed.

       "st_dev_size"
           From st_dev_def.U:

           This variable contains the size of struct stat's st_dev in bytes.

       "st_ino_sign"
           From st_ino_def.U:

           This variable contains the signedness of struct  stat's  st_ino.   1
           for unsigned, -1 for signed.

       "st_ino_size"
           From st_ino_def.U:

           This variable contains the size of struct stat's st_ino in bytes.

       "startperl"
           From startperl.U:

           This  variable  contains  the  string  to put on the front of a perl
           script to make sure (hopefully) that it runs with perl and not  some
           shell.  Of  course,  that  leading  line  must  be  followed  by the
           classical  perl  idiom:  eval  'exec  perl   -S   $0   ${1+$@}'   if
           $running_under_some_shell;  to  guarantee  perl  startup  should the
           shell execute the script. Note that this magic  incantation  is  not
           understood by csh.

       "startsh"
           From startsh.U:

           This  variable  contains  the  string to put on the front of a shell
           script to make sure (hopefully) that it runs with sh  and  not  some
           other shell.

       "static_ext"
           From Extensions.U:

           This  variable  holds a list of "XS" extension files we want to link
           statically into the package.  It is used by Makefile.

       "stdchar"
           From stdchar.U:

           This variable conditionally defines "STDCHAR" to be the type of char
           used in stdio.h.  It has the values "unsigned char" or "char".

       "stdio_base"
           From d_stdstdio.U:

           This variable defines how, given a "FILE" pointer, fp, to access the
           _base field (or equivalent) of  stdio.h's  "FILE"  structure.   This
           will be used to define the macro FILE_base(fp).

       "stdio_bufsiz"
           From d_stdstdio.U:

           This  variable defines how, given a "FILE" pointer, fp, to determine
           the number of bytes store in the I/O buffer pointer to by the  _base
           field  (or  equivalent) of stdio.h's "FILE" structure.  This will be
           used to define the macro FILE_bufsiz(fp).

       "stdio_cnt"
           From d_stdstdio.U:

           This variable defines how, given a "FILE" pointer, fp, to access the
           _cnt field (or equivalent) of stdio.h's "FILE" structure.  This will
           be used to define the macro FILE_cnt(fp).

       "stdio_filbuf"
           From d_stdstdio.U:

           This variable defines how, given a "FILE" pointer, fp, to tell stdio
           to refill its internal buffers (?).  This will be used to define the
           macro FILE_filbuf(fp).

       "stdio_ptr"
           From d_stdstdio.U:

           This variable defines how, given a "FILE" pointer, fp, to access the
           _ptr field (or equivalent) of stdio.h's "FILE" structure.  This will
           be used to define the macro FILE_ptr(fp).

       "stdio_stream_array"
           From stdio_streams.U:

           This variable tells the name of the array holding the stdio streams.
           Usual values include _iob, __iob, and __sF.

       "strerror_r_proto"
           From d_strerror_r.U:

           This variable encodes the prototype of strerror_r.  It  is  zero  if
           d_strerror_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_strerror_r is defined.

       "submit"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "subversion"
           From patchlevel.U:

           The subversion level of this package.  The value of subversion comes
           from the patchlevel.h file.  In a version number such as 5.6.1, this
           is   the   1.    In   patchlevel.h,   this   is   referred   to   as
           "PERL_SUBVERSION".  This is unique to perl.

       "sysman"
           From sysman.U:

           This  variable  holds  the place where the manual is located on this
           system. It is not the place where the user wants to put  his  manual
           pages.  Rather  it  is  the  place  where Configure may look to find
           manual for unix commands (section 1  of  the  manual  usually).  See
           mansrc.

       "sysroot"
           From Sysroot.U:

           This  variable  is  empty unless supplied by the Configure user.  It
           can contain a path to an alternative  root  directory,  under  which
           headers  and libraries for the compilation target can be found. This
           is generally used when cross-compiling using a gcc-like compiler.

   t
       "tail"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "taint_disabled"
           From define: "SILENT_NO_TAINT_SUPPORT" or "NO_TAINT_SUPPORT"

           If  this  perl is compiled with support for taint mode this variable
           will  be  set  to  the  empty  string,  if  it  was  compiled   with
           "SILENT_NO_TAINT_SUPPORT"   defined  then  it  will  be  set  to  be
           "silent", and if it was compiled with "NO_TAINT_SUPPORT" defined  it
           will  be  'define'.  Either  of the above defines will results in it
           being a true value. This property was added  in  5.37.11.  See  also
           "taint_support".

       "taint_support"
           From define: "SILENT_NO_TAINT_SUPPORT" or "NO_TAINT_SUPPORT"

           If  this  perl is compiled with support for taint mode this variable
           will be set to 'define', if it is not it will be set  to  the  empty
           string.   Either of the above defines will result in it being empty.
           This   property   was   added   in   version   5.37.11.   See   also
           "taint_disabled".

       "tar"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "targetarch"
           From Cross.U:

           If cross-compiling, this variable contains the target  architecture.
           If not, this will be empty.

       "targetdir"
           From Cross.U:

           This  variable  contains  a  path that will be created on the target
           host using targetmkdir, and then used  to  copy  the  cross-compiled
           executables to. Defaults to /tmp if not set.

       "targetenv"
           From Cross.U:

           If  cross-compiling,  this  variable  can  be  used  to  modify  the
           environment on the target system.  However, how and where it's used,
           and even if it's used at all, is  entirely  dependent  on  both  the
           transport  mechanism  (targetrun)  and  what  the  target system is.
           Unless the relevant documentation says otherwise, it  is  genereally
           not useful.

       "targethost"
           From Cross.U:

           This  variable contains the name of a separate host machine that can
           be used to run compiled test programs and perl  tests  on.   Set  to
           empty string if not in use.

       "targetmkdir"
           From Cross.U:

           This variable contains the command used by Configure to create a new
           directory on the target host.

       "targetport"
           From Cross.U:

           This  variable  contains  the number of a network port to be used to
           connect to the host in targethost, if unset defaults to 22 for ssh.

       "targetsh"
           From sh.U:

           If cross-compiling, this variable contains the location of sh on the
           target system.  If not, this will be the same as $sh.

       "tbl"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "tee"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "test"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of the test program.  After Configure runs, the
           value is reset to a plain "test" and is not useful.

       "timeincl"
           From i_time.U:

           This variable holds the full path of the included time header(s).

       "timetype"
           From d_time.U:

           This variable holds the type returned by time(). It can be long,  or
           time_t  on  "BSD"  sites  (in  which  case  <sys/types.h>  should be
           included). Anyway, the type Time_t should be used.

       "tmpnam_r_proto"
           From d_tmpnam_r.U:

           This variable encodes the prototype of  tmpnam_r.   It  is  zero  if
           d_tmpnam_r  is  undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_tmpnam_r is defined.

       "to"
           From Cross.U:

           This variable contains the command used by Configure to copy to from
           the target host.  Useful and available only during Perl build.   The
           string ":" if not cross-compiling.

       "touch"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the touch program.  After Configure  runs,  the
           value is reset to a plain "touch" and is not useful.

       "tr"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the tr  program.   After  Configure  runs,  the
           value is reset to a plain "tr" and is not useful.

       "trnl"
           From trnl.U:

           This  variable  contains the value to be passed to the tr(1) command
           to transliterate a newline.  Typical values  are  "\012"  and  "\n".
           This is needed for "EBCDIC" systems where newline is not necessarily
           "\012".

       "troff"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

       "ttyname_r_proto"
           From d_ttyname_r.U:

           This variable encodes the prototype of ttyname_r.   It  is  zero  if
           d_ttyname_r  is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
           of reentr.h if d_ttyname_r is defined.

   u
       "u16size"
           From perlxv.U:

           This variable is the size of an U16 in bytes.

       "u16type"
           From perlxv.U:

           This variable contains the C type used for Perl's U16.

       "u32XUformat"
           From perlx32f.U:

           This variable contains the format string used for  printing  a  Perl
           U32 as an unsigned hexadecimal integer in uppercase "ABCDEF".

       "u32oformat"
           From perlx32f.U:

           This  variable  contains  the format string used for printing a Perl
           U32 as an unsigned octal integer.

       "u32size"
           From perlxv.U:

           This variable is the size of an U32 in bytes.

       "u32type"
           From perlxv.U:

           This variable contains the C type used for Perl's U32.

       "u32uformat"
           From perlx32f.U:

           This variable contains the format string used for  printing  a  Perl
           U32 as an unsigned decimal integer.

       "u32xformat"
           From perlx32f.U:

           This  variable  contains  the format string used for printing a Perl
           U32 as an unsigned hexadecimal integer in lowercase abcdef.

       "u64size"
           From perlxv.U:

           This variable is the size of an U64 in bytes.

       "u64type"
           From perlxv.U:

           This variable contains the C type used for Perl's U64.

       "u8size"
           From perlxv.U:

           This variable is the size of an U8 in bytes.

       "u8type"
           From perlxv.U:

           This variable contains the C type used for Perl's U8.

       "uidformat"
           From uidf.U:

           This variable contains the format string used for printing a Uid_t.

       "uidsign"
           From uidsign.U:

           This variable contains the signedness of a uidtype.  1 for unsigned,
           -1 for signed.

       "uidsize"
           From uidsize.U:

           This variable contains the size of a uidtype in bytes.

       "uidtype"
           From uidtype.U:

           This variable defines Uid_t to be something like uid_t, int, ushort,
           or whatever type is used to declare user ids in the kernel.

       "uname"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any) of the uname program.  After Configure runs, the
           value is reset to a plain "uname" and is not useful.

       "uniq"
           From Loc.U:

           This variable is used internally by Configure to determine the  full
           pathname  (if  any)  of the uniq program.  After Configure runs, the
           value is reset to a plain "uniq" and is not useful.

       "uquadtype"
           From quadtype.U:

           This variable defines Uquad_t to be something  like  unsigned  long,
           unsigned int, unsigned long long, uint64_t, or whatever type is used
           for 64-bit integers.

       "use64bitall"
           From use64bits.U:

           This  variable  conditionally defines the USE_64_BIT_ALL symbol, and
           indicates that 64-bit integer types should be used  when  available.
           The  maximal possible 64-bitness is employed: LP64 or ILP64, meaning
           that you will be able to use more than 2 gigabytes of memory.   This
           mode  is  even more binary incompatible than USE_64_BIT_INT. You may
           not be able to run the resulting executable in a 32-bit "CPU" at all
           or you may need at least to reboot your "OS" to 64-bit mode.

       "use64bitint"
           From use64bits.U:

           This variable conditionally defines the USE_64_BIT_INT  symbol,  and
           indicates  that  64-bit integer types should be used when available.
           The minimal possible 64-bitness is  employed,  just  enough  to  get
           64-bit  integers  into  Perl.  This may mean using for example "long
           longs", while your memory may still be limited to 2 gigabytes.

       "usecbacktrace"
           From usebacktrace.U:

           This variable indicates whether  we  are  compiling  with  backtrace
           support.

       "usecrosscompile"
           From Cross.U:

           This  variable conditionally defines the "USE_CROSS_COMPILE" symbol,
           and indicates that Perl has been cross-compiled.

       "usedefaultstrict"
           From usedefaultstrict.U:

           This setting provides a mechanism  for  perl  developers  to  enable
           strict  by default. These defaults do not apply when perl is run via
           -e or -E.

       "usedevel"
           From Devel.U:

           This variable indicates that Perl was  configured  with  development
           features enabled.  This should not be done for production builds.

       "usedl"
           From dlsrc.U:

           This  variable  indicates  if the system supports dynamic loading of
           some sort.  See also dlsrc and dlobj.

       "usedtrace"
           From usedtrace.U:

           This  variable  indicates  whether  we  are  compiling  with  dtrace
           support. See also dtrace.

       "usefaststdio"
           From usefaststdio.U:

           This variable conditionally defines the "USE_FAST_STDIO" symbol, and
           indicates  that  Perl should be built to use "fast stdio".  Defaults
           to define in Perls 5.8 and earlier, to undef later.

       "useithreads"
           From usethreads.U:

           This variable conditionally defines the "USE_ITHREADS"  symbol,  and
           indicates  that  Perl  should  be built to use the interpreter-based
           threading implementation.

       "usekernprocpathname"
           From usekernprocpathname.U:

           This   variable,   indicates   that   we   can   use   sysctl   with
           "KERN_PROC_PATHNAME"  to  get  a  full  path for the executable, and
           hence convert $^X to an absolute path.

       "uselanginfo"
           From Extensions.U:

           This variable holds either "true" or "false" to indicate whether the
           I18N::Langinfo extension should be used.   The  sole  use  for  this
           currently  is  to  allow  an  easy  mechanism for users to skip this
           extension from the Configure command line.

       "uselargefiles"
           From uselfs.U:

           This variable conditionally defines  the  "USE_LARGE_FILES"  symbol,
           and  indicates  that  large  file  interfaces  should  be  used when
           available.

       "uselongdouble"
           From uselongdbl.U:

           This variable conditionally defines  the  "USE_LONG_DOUBLE"  symbol,
           and indicates that long doubles should be used when available.

       "usemallocwrap"
           From mallocsrc.U:

           This  variable  contains  y  if  we  are  wrapping malloc to prevent
           integer overflow during size calculations.

       "usemorebits"
           From usemorebits.U:

           This variable conditionally defines the "USE_MORE_BITS" symbol,  and
           indicates that explicit 64-bit interfaces and long doubles should be
           used when available.

       "usemultiplicity"
           From usemultiplicity.U:

           This  variable  conditionally defines the "MULTIPLICITY" symbol, and
           indicates that Perl should be built to use multiplicity.

       "usemymalloc"
           From mallocsrc.U:

           This variable contains y if the malloc that comes with this  package
           is  desired  over  the  system's  version  of  malloc.  People often
           include special versions of malloc for efficiency, but such versions
           are often less portable.  See also mallocsrc and mallocobj.  If this
           is "y", then -lmalloc is removed from $libs.

       "usenm"
           From usenm.U:

           This variable contains "true" or "false" depending  whether  the  nm
           extraction is wanted or not.

       "usensgetexecutablepath"
           From usensgetexecutablepath.U:

           This    symbol,    if   defined,   indicates   that   we   can   use
           _NSGetExecutablePath and  realpath  to  get  a  full  path  for  the
           executable, and hence convert $^X to an absolute path.

       "useopcode"
           From Extensions.U:

           This variable holds either "true" or "false" to indicate whether the
           Opcode extension should be used.  The sole use for this currently is
           to  allow  an  easy mechanism for users to skip the Opcode extension
           from the Configure command line.

       "useperlio"
           From useperlio.U:

           This variable conditionally defines  the  "USE_PERLIO"  symbol,  and
           indicates that the PerlIO abstraction should be used throughout.

       "useposix"
           From Extensions.U:

           This variable holds either "true" or "false" to indicate whether the
           "POSIX"  extension  should be used.  The sole use for this currently
           is to allow an easy mechanism  for  hints  files  to  indicate  that
           "POSIX" will not compile on a particular system.

       "usequadmath"
           From usequadmath.U:

           This  variable  conditionally defines the "USE_QUADMATH" symbol, and
           indicates that the quadmath library __float128 long  doubles  should
           be used when available.

       "usereentrant"
           From usethreads.U:

           This  variable conditionally defines the "USE_REENTRANT_API" symbol,
           which indicates that the thread code may try to use the  various  _r
           versions  of library functions.  This is only potentially meaningful
           if usethreads is set and  is  very  experimental,  it  is  not  even
           prompted for.

       "userelocatableinc"
           From bin.U:

           This  variable  is set to true to indicate that perl should relocate
           @"INC" entries at runtime based on the path to the perl binary.  Any
           @"INC" paths starting .../ are relocated relative to  the  directory
           containing  the  perl  binary,  and a logical cleanup of the path is
           then made around the join point (removing dir/../ pairs)

       "useshrplib"
           From libperl.U:

           This variable is set to "true" if the user wishes to build a  shared
           libperl, and "false" otherwise.

       "usesitecustomize"
           From d_sitecustomize.U:

           This variable is set to true when the user requires a mechanism that
           allows  the  sysadmin  to  add  entries  to @"INC" at runtime.  This
           variable being set,  makes  perl  run  $sitelib/sitecustomize.pl  at
           startup.

       "usesocks"
           From usesocks.U:

           This  variable  conditionally  defines  the  "USE_SOCKS" symbol, and
           indicates that Perl should be built to use "SOCKS".

       "usethreads"
           From usethreads.U:

           This variable conditionally defines the  "USE_THREADS"  symbol,  and
           indicates that Perl should be built to use threads.

       "usevendorprefix"
           From vendorprefix.U:

           This  variable tells whether the vendorprefix and consequently other
           vendor* paths are in use.

       "useversionedarchname"
           From archname.U:

           This variable indicates whether to include the $api_versionstring as
           a component of the $archname.

       "usevfork"
           From d_vfork.U:

           This variable is set to true when the user accepts to use vfork.  It
           is set to false  when  no  vfork  is  available  or  when  the  user
           explicitly requests not to use vfork.

       "usrinc"
           From usrinc.U:

           This  variable holds the path of the include files, which is usually
           /usr/include. It is mainly used by other Configure units.

       "uuname"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "uvXUformat"
           From perlxvf.U:

           This  variable  contains  the format string used for printing a Perl
           "UV" as an unsigned hexadecimal integer in uppercase "ABCDEF".

       "uvoformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "UV" as an unsigned octal integer.

       "uvsize"
           From perlxv.U:

           This variable is the size of a "UV" in bytes.

       "uvtype"
           From perlxv.U:

           This variable contains the C type used for Perl's "UV".

       "uvuformat"
           From perlxvf.U:

           This  variable  contains  the format string used for printing a Perl
           "UV" as an unsigned decimal integer.

       "uvxformat"
           From perlxvf.U:

           This variable contains the format string used for  printing  a  Perl
           "UV" as an unsigned hexadecimal integer in lowercase abcdef.

   v
       "vendorarch"
           From vendorarch.U:

           This  variable  contains  the value of the "PERL_VENDORARCH" symbol.
           It may have a ~ on the front.  The standard  distribution  will  put
           nothing  in this directory.  Vendors who distribute perl may wish to
           place their own architecture-dependent  modules  and  extensions  in
           this  directory  with  MakeMaker Makefile.PL "INSTALLDIRS"=vendor or
           equivalent.  See "INSTALL" for details.

       "vendorarchexp"
           From vendorarch.U:

           This variable is the ~name expanded version of vendorarch,  so  that
           you may use it directly in Makefiles or shell scripts.

       "vendorbin"
           From vendorbin.U:

           This variable contains the eventual value of the "VENDORBIN" symbol.
           It  may  have  a ~ on the front.  The standard distribution will put
           nothing in this directory.  Vendors who distribute perl may wish  to
           place   additional   binaries   in  this  directory  with  MakeMaker
           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See  "INSTALL"  for
           details.

       "vendorbinexp"
           From vendorbin.U:

           This  variable  is  the ~name expanded version of vendorbin, so that
           you may use it directly in Makefiles or shell scripts.

       "vendorhtml1dir"
           From vendorhtml1dir.U:

           This variable contains the name of the directory for html pages.  It
           may have a ~ on the  front.   The  standard  distribution  will  put
           nothing  in this directory.  Vendors who distribute perl may wish to
           place  their  own  html  pages  in  this  directory  with  MakeMaker
           Makefile.PL  "INSTALLDIRS"=vendor  or equivalent.  See "INSTALL" for
           details.

       "vendorhtml1direxp"
           From vendorhtml1dir.U:

           This variable is the ~name expanded version  of  vendorhtml1dir,  so
           that you may use it directly in Makefiles or shell scripts.

       "vendorhtml3dir"
           From vendorhtml3dir.U:

           This  variable  contains  the name of the directory for html library
           pages.  It may have a ~ on the  front.   The  standard  distribution
           will put nothing in this directory.  Vendors who distribute perl may
           wish  to  place  their  own html pages for modules and extensions in
           this directory with MakeMaker  Makefile.PL  "INSTALLDIRS"=vendor  or
           equivalent.  See "INSTALL" for details.

       "vendorhtml3direxp"
           From vendorhtml3dir.U:

           This  variable  is  the ~name expanded version of vendorhtml3dir, so
           that you may use it directly in Makefiles or shell scripts.

       "vendorlib"
           From vendorlib.U:

           This variable contains the eventual value of the "VENDORLIB" symbol,
           which is the name of the private  library  for  this  package.   The
           standard  distribution  will put nothing in this directory.  Vendors
           who distribute perl may wish to place  their  own  modules  in  this
           directory   with   MakeMaker   Makefile.PL  "INSTALLDIRS"=vendor  or
           equivalent.  See "INSTALL" for details.

       "vendorlib_stem"
           From vendorlib.U:

           This variable is $vendorlibexp with  any  trailing  version-specific
           component     removed.     The    elements    in    inc_version_list
           (inc_version_list.U) can be tacked onto this variable to generate  a
           list of directories to search.

       "vendorlibexp"
           From vendorlib.U:

           This  variable  is  the ~name expanded version of vendorlib, so that
           you may use it directly in Makefiles or shell scripts.

       "vendorman1dir"
           From vendorman1dir.U:

           This variable contains the name of the directory for man1 pages.  It
           may have a ~ on the  front.   The  standard  distribution  will  put
           nothing  in this directory.  Vendors who distribute perl may wish to
           place  their  own  man1  pages  in  this  directory  with  MakeMaker
           Makefile.PL  "INSTALLDIRS"=vendor  or equivalent.  See "INSTALL" for
           details.

       "vendorman1direxp"
           From vendorman1dir.U:

           This variable is the ~name expanded  version  of  vendorman1dir,  so
           that you may use it directly in Makefiles or shell scripts.

       "vendorman3dir"
           From vendorman3dir.U:

           This variable contains the name of the directory for man3 pages.  It
           may  have  a  ~  on  the  front.  The standard distribution will put
           nothing in this directory.  Vendors who distribute perl may wish  to
           place  their  own  man3  pages  in  this  directory  with  MakeMaker
           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See  "INSTALL"  for
           details.

       "vendorman3direxp"
           From vendorman3dir.U:

           This  variable  is  the  ~name expanded version of vendorman3dir, so
           that you may use it directly in Makefiles or shell scripts.

       "vendorprefix"
           From vendorprefix.U:

           This variable holds the full absolute path of  the  directory  below
           which  the  vendor  will install add-on packages.  See "INSTALL" for
           usage and examples.

       "vendorprefixexp"
           From vendorprefix.U:

           This variable holds the full absolute path of  the  directory  below
           which  the  vendor  will  install  add-on  packages.   Derived  from
           vendorprefix.

       "vendorscript"
           From vendorscript.U:

           This variable contains the  eventual  value  of  the  "VENDORSCRIPT"
           symbol.   It  may  have a ~ on the front.  The standard distribution
           will put nothing in this directory.  Vendors who distribute perl may
           wish to place additional executable scripts in this  directory  with
           MakeMaker   Makefile.PL  "INSTALLDIRS"=vendor  or  equivalent.   See
           "INSTALL" for details.

       "vendorscriptexp"
           From vendorscript.U:

           This variable is the ~name expanded version of vendorscript, so that
           you may use it directly in Makefiles or shell scripts.

       "version"
           From patchlevel.U:

           The full version number of this package, such as 5.6.1  (or  5_6_1).
           This  combines  revision, patchlevel, and subversion to get the full
           version  number,  including  any  possible  subversions.   This   is
           suitable  for  use  as  a  directory  name,  and hence is filesystem
           dependent.

       "version_patchlevel_string"
           From patchlevel.U:

           This is a string combining version, subversion  and  perl_patchlevel
           (if  perl_patchlevel  is  non-zero).  It is typically something like
           'version 7 subversion 1'  or  'version  7  subversion  1  patchlevel
           11224'  It  is  computed  here  to  avoid  duplication  of  code  in
           myconfig.SH and lib/Config.pm.

       "versiononly"
           From versiononly.U:

           If  set,  this  symbol  indicates  that  only  the  version-specific
           components  of a perl installation should be installed.  This may be
           useful for making a test  installation  of  a  new  version  without
           disturbing   the  existing  installation.   Setting  versiononly  is
           equivalent to setting installperl's -v option.  In  particular,  the
           non-versioned  scripts  and programs such as a2p, c2ph, h2xs, pod2*,
           and perldoc are not installed (see "INSTALL"  for  a  more  complete
           list).  Nor are the man pages installed.  Usually, this is undef.

       "vi"
           From Loc.U:

           This  variable  is  defined but not used by Configure.  The value is
           the empty string and is not useful.

   x
       "xlibpth"
           From libpth.U:

           This variable  holds  extra  path  (space-separated)  used  to  find
           libraries on this platform, for example "CPU"-specific libraries (on
           multi-"CPU" platforms) may be listed here.

       "xlocale_needed"
           From d_newlocale.U:

           This symbol, if defined, indicates that the C program should include
           <xlocale.h> to get newlocale() and its friends.

   y
       "yacc"
           From yacc.U:

           This variable holds the name of the compiler compiler we want to use
           in the Makefile. It can be yacc, byacc, or bison -y.

       "yaccflags"
           From yacc.U:

           This  variable  contains  any  additional  yacc flags desired by the
           user.  It is up to the Makefile to use this.

   z
       "zcat"
           From Loc.U:

           This variable is defined but not used by Configure.   The  value  is
           the empty string and is not useful.

       "zip"
           From Loc.U:

           This  variable is used internally by Configure to determine the full
           pathname (if any) of the zip program.   After  Configure  runs,  the
           value is reset to a plain "zip" and is not useful.

GIT DATA
       Information  on  the  git  commit from which the current perl binary was
       compiled can be found in the variable $Config::Git_Data.   The  variable
       is a structured string that looks something like this:

         git_commit_id='ea0c2dbd5f5ac6845ecc7ec6696415bf8e27bd52'
         git_describe='GitLive-blead-1076-gea0c2db'
         git_branch='smartmatch'
         git_uncommitted_changes=''
         git_commit_id_title='Commit id:'
         git_commit_date='2009-05-09 17:47:31 +0200'

       Its format is not guaranteed not to change over time.

NOTE
       This  module  contains  a  good example of how to use tie to implement a
       cache and an example of how to make a tied variable  readonly  to  those
       outside of it.

perl v5.40.1                       2026-08-30                     Config(3perl)

Generated by dwww version 1.16 on Sat Oct 3 10:25:01 CEST 2026.