subprocesses System can use subprocesses (for M-x shell for example). Defined by default, only MSDOS undefines it.
USE_LISP_UNION_TYPE Define it in lisp.h to make Lisp_Object be a union type instead of the default int.
+** System specific macros, decribed in detail in src/s/template.h
+BSTRING
+CLASH_DETECTION
+COFF
+FIRST_PTY_LETTER
+HAVE_PTYS
+HAVE_TERMIO
+HAVE_TERMIOS
+INTERRUPT_INPUT
+MAIL_USE_FLOCK
+NARROWPROTO
+NOMULTIPLEJOBS
+SEPCHAR
+SIGTYPE
+SYSTEM_TYPE
+USE_MMAP_FOR_BUFFERS
+
+** Machine specific macros, decribed in detail in src/m/template.h
+CANNOT_DUMP
+EXPLICIT_SIGN_EXTEND
+LOAD_AVE_CVT
+LOAD_AVE_TYPE
+NO_ARG_ARRAY
+NO_REMAP
+NO_SOCK_SIGIO
+VIRT_ADDR_VARIES
+WORDS_BIG_ENDIAN
+
** Misc macros
USER_FULL_NAME If defined, overrides the default pw->pw_gecos for getting at the full user name. Only MSDOS overrides the default.
BSD4_3
BSD_PGRPS
BSD_SYSTEM
-BSTRING
-CANNOT_DUMP
CLASH_DETECTION
-COFF
COFF_BSD_SYMBOLS
CRT0_DUMMIES
C_DEBUG_SWITCH
EMACS_INT
EMACS_UINT
END_FILES_1
-EXPLICIT_SIGN_EXTEND
FILE_SYSTEM_CASE
-FIRST_PTY_LETTER
FLOAT_CHECK_DOMAIN
FSCALE
GAP_USE_BCOPY
HAVE_MOUSE
HAVE_PERROR
HAVE_PSTAT_GETDYNAMIC
-HAVE_PTYS
HAVE_PWD_H
HAVE_RANDOM
HAVE_RENAME
HAVE_SYS_TIMEB_H
HAVE_SYS_TIME_H
HAVE_TCATTR
-HAVE_TERMIO
-HAVE_TERMIOS
HAVE_TERMIOS_H
HAVE_TEXT_START
HAVE_TIMEVAL
IBMR2AIX
INHIBIT_X11R6_XIM
INTERNAL_TERMINAL
-INTERRUPT_INPUT
IS_ANY_SEP
IS_DIRECTORY_SEP
KERNEL_FILE
LINUX_VERSION_CODE
LISP_FLOAT_TYPE
LNOFLSH
-LOAD_AVE_CVT
-LOAD_AVE_TYPE
LOCALTIME_CACHE
-MAIL_USE_FLOCK
MAIL_USE_LOCKF
MAIL_USE_POP
MAIL_USE_SYSTEM_LOCK
MIN_PTY_KERNEL_VERSION -- only used on Mac
MODE_LINE_BINARY_TEXT
MUST_UNDEF__STDC__
-NARROWPROTO
NEED_BSDTTY
NEED_ERRNO
NEED_LIBW
NEED_UNISTD_H
NLIST_STRUCT
-NOMULTIPLEJOBS
NOT_C_CODE
NOT_USING_MOTIF
NO_ABORT
-NO_ARG_ARRAY
NO_DIR_LIBRARY
NO_EDITRES
NO_MATHERR
-NO_REMAP
NO_SHARED_LIBS
-NO_SOCK_SIGIO
NO_TERMIO
NSIG
NSIG_MINIMUM
SA_RESTART
SECTION_ALIGNMENT
SEGMENT_MASK
-SEPCHAR
SETPGRP_RELEASES_CTTY
SETUP_SLAVE_PTY
SIGALRM
STDC_HEADERS
SYMS_SYSTEM
SYSTEM_PURESIZE_EXTRA
-SYSTEM_TYPE
SYSTEM_MALLOC
SYSV_SYSTEM_DIR
Srandom
UNIX98_PTYS
USE_CRT_DLL
USE_MAC_IMAGE_IO
-USE_MMAP_FOR_BUFFERS
USE_TOOLKIT_SCROLL_BARS
USG
USG5
USG5_4
USG_SUBTTY_WORKS
VALBITS
-VIRT_ADDR_VARIES
WORDS_BIG_ENDIAN
WRETCODE
XINT