cpp reserved symbols

[Mike Muuss]

The list of "possibly reserved symbols" is amazingly long.   You find
it by the experimental method, as you port code around. Some that I know
of include:

unix, vax, m68k, m68000, alliant, sel, gould, sgi, mips,
sun, sun3, sparc, apollo, CRAY, CRAY1, CRAY2, convex, ardent,
stellar, eta10, pyr.

The ANSI-C specification calls for vendor-provided symbols to begin
with an underscore and an upper-case letter.  For example, _CRAY,
_Vax, etc.  This is a good idea, but will result in a whole
new raft of symbols being defined.  Along with __STDC__.

There are other pitfalls as well, like when you need <time.h>,
when you need <sys/time.h>, and when you need both.  Arrgh!

	Best,
	 -Mike