__DJGPP_MINOR__ Minor version number of the DJGPP library; used only in msdos.c and dosfns.c.
DOS_NT Compiling for either the MS-DOS or native MS-Windows port.
WINDOWSNT Compiling the native MS-Windows (W32) port.
-__MINGW32__ Compiling the W32 port with the MinGW port of GCC.
+__MINGW32__ Compiling the W32 port with the MinGW or MinGW-w64 ports of GCC.
_MSC_VER Compiling the W32 port with the Microsoft C compiler.
+MINGW_W64 Compiling the W32 port with the MinGW-w64 port of GCC.
DARWIN_OS Compiling on Mac OS X or pure Darwin (and using s/darwin.h).
SOLARIS2
USG
INTERNAL_TERMINAL
IS_ANY_SEP
IS_DIRECTORY_SEP
-LOCALTIME_CACHE
MAIL_USE_FLOCK
MAIL_USE_LOCKF
MAIL_USE_POP