.h vs .hug

I have to admit that for a long time, I've been kind of confused about when an included Hugo file should have the extension ".h" and when it should have ".hug". I mean, the hugolib library files are obviously all *.h and a shell file is always *.hug, but why, for instance, did all of the Future Boy Selected Source files use the *.hug extension when several seem to be relatively includable (and are comprised of utility routines and object classes and such).

I've recently decided on the distinction that the *.h extension is reserved for files that have gone the extra mile and have inclusion-specific code like:

#ifclear _ROODYLIB_H
#set _ROODYLIB_H

What this means for Hugo-by-Example-hosted files is that while most of my library contributions will remain the same, some of the Future Boy! contributions like "books", "time", "context_menu", and "config" are going back to their original *.hug extension.

I may change "version.h" back to *.hug at some point, too, as as far as contributions go, that one is very short and likely to be modified by the author.