Re: [Bug-gnulib] serial numbers in .m4 files: are they still useful?

[Karl Berry]

    You could always switch to the RCS "$Revision$" keyword now that your 
    sources are in CVS.  That wouldn't need to be maintained so manually.

As it happens, I proposed using that (well, $Id$) in the past (for other
reasons), but got shot down because the sources are moved around to
different revision systems and hence the checkin version varies.

To get around this, a datestamp (YYYYMMDD.HHMM or some such) could be
used, updated automatically with time-stamp.el or similar.  This is done
for texinfo.tex, mkinstalldirs, and many other scripts these days.