rfc: WIN32 vs _WIN32 and more

[walter harms]

Hi list,
is there a common ground for using OS related defines ?
I was look at some libs and found some defines that
look pretty ancient. And some like
WIN32 vs _WIN32
seems to confuse other people also ( ask you search engine)

I found also:
ISC  *
MOTOROLA *
VMS    *
USG    *
hpux
sgi
sparc
sun
ultrix *
__osf__ *


* dead ?

For easier maintainability i would like to remove defines that are not
in use any more.

re,
 wh