V10/lbin/kermit/ckcsym.h

/* This file is for use with compilers that don't have the capability to
 * #define symbols on the C compiler command line.  This file must
 * be #include'd before all other ck*.h files so that the symbols #define'd
 * here can be used for any subsequent conditional code.  Symbols should be
 * #define'd as 1 if TRUE and 0 if FALSE.  This implies, of course, that they
 * be tested with #if's, not #ifdef's and #ifndef's.
 */ 

/*
 * For example, this file was required to compile Macintosh Kermit under
 * Megamax C (which we don't do any more), because Megamax did not have
 * a mechanism for defining symbols on the command line, so this file was
 * used to define the symbol MAC.
 */