version control handling documentation bug

[Harvey J. Stein]

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Please write in English, because the Emacs maintainers do not have
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In GNU Emacs 20.7.1 (i386-redhat-linux-gnu, X toolkit)
 of Tue Jun 13 2000 on porky.devel.redhat.com
configured using `configure  --mandir=/usr/man --infodir=/usr/info 
--prefix=/usr --libexecdir=/usr/lib --sharedstatedir=/var --with-gcc --with-pop 
--with-x-toolkit i386-redhat-linux-gnu'

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

The emacs info pages for version 20.7 says (on the (Old Versions)
node) that C-x v = compares the current buffer contents with the
latest checked-in version of the file.

I found "latest checked-in version" to be unclear.  I read it as
meaning the version control head revision, but it's not always this.
It seems to be the source controlled version of the file.  That is to
say, based on empirical testing, it seems to be the revision in source
control corresponding to whatever revision emacs thinks the current
buffer is based on.

So, for example, when using RCS, if there are versions 1.1 through 1.6
in RCS, and there are no RCS ID tags in the file, emacs will assume
the file is based on the latest version in RCS (namely 1.6) and will
diff against it.

If the appropriate RCS tags are at the top of the file, and, for
example, they refer to version 1.4, then emacs assumes the current
buffer is based on version 1.4, and will then diff against version
1.4.

The same presumably applies to other commands which work with the
"latest" version.  It's true of `C-x v u'.  I didn't check `C-x v c'.

I can understand why this behavior was chosen - although it's not, for
example what rcsdiff would do, it *is* what cvs diff does, and it can
be argued that this probably what people want most of the time.

However, it would be nice to *also* be able to revert to the head
version and compare against the head version, and I didn't find any
way within emacs to do that aside from explicitly giving the version
number of the head revision.

Thanks.

Recent input:
g SPC q SPC n n n n n n n q SPC q SPC n n n n q 2 g 
s switch-frame u u u C-s b u g C-r C-r C-r C-a return 
SPC C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n SPC SPC switch-frame escape x r 
e p o r t SPC e m a SPC b u g return

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-- 
Harvey Stein
Bloomberg LP
hjstein@bloomberg.com