*BSD use of branch point tags w/ CVS

[Claude Johnson]

>From reading some of the docs about NetBSD's and FreeBSD's
release processes, I have noticed that they both use what
FreeBSD calls "branch point" tags. Not having a lot of
experience with CVS, I don't quite understand what problem
is solved by doing this. The FreeBSD release docs claim
that it is impossible to diff against the start of a branch
w/o a branch point tag in place.

The process appears to look something like this:

        1. Create branch point tag

                cvs rtag <tag>_BP src

        2. Create the actual branch

                cvs rtag -b -r<tag>_BP <tag> src

Is this an old CVS quirk that has been fixed, or does this
problem still exist? What _exactly_ is the problem? An
example or ideas on how I could reproduce the problem in my
own CVS environment would be welcome.

Thanks in advance!


Claude Johnson
Network Scientist
Avamar Technologies
949.743.5145 Vox
949.743.5190 Fax
www.avamar.com