_NO_WFLAGS This oprion compiles out the wflag code, thus saves memory for the compilers that produce limited memory versions. Wflags may still be read in, but they will be ignored and not saved DOS_MACHINE If you are compiling on an IBM machine running any version of DOS then you need to define this. EQBUG Define this if your compiler does not have libraries with the functions strncasecmp() and strcasecmp() ANSI_C This ensures that ansi C style prototypes are used rather than the default OLD C type. Few other things change as well. PCC_286 The pcc compiler is not capable of certain things. In particular this will disable the ability to save a comment at the start of the zone. IBM_MLJ_EDIT Compile the simple editor and use it for getting long text decriptions from the user. NOTE that this uses commands found in the IBM GNU C Compiler (djgpp) and these may or may not be available or do the same things with other compilers.