standards for include guards?

[Sam TH]

Without getting into a discussion on the merits of include guards in
GCC, is there some standard for naming such guards?  With the help of
grep, I have found:

 _FILENAME_EXT
 GCC_FILENAME_EXT
 __GCC_FILENAME_EXT__
 _GCC_FILENAME_EXT
 __FILENAME_EXT__
 __filename_ext
 FILENAME_EXT_INCLUDED
 FILENAME_EXT
 _FILENAME_EXT_
 JV_FILENAME_EXT (in java/)
 _DIR_FILENAME_EXT
 _H_f_filename (in f/)
  
Then, the weird ones:
java/parse.h: JV_LANG_H 
gstab.h: __GNU_STAB__
glimits.h: __LIMITS_H_

Maybe something should be picked?
           
sam th --- sam@uchicago.edu --- http://www.abisource.com/~sam/
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