5.5 Magic branch numbers

This section describes a CVS feature called magic branches. For most purposes, you need not worry about magic branches; CVS handles them for you. However, they are visible to you in certain circumstances, so it may be useful to have some idea of how it works.

Externally, branch numbers consist of an odd number of dot-separated decimal integers. See Revision numbers. That is not the whole truth, however. For efficiency reasons CVS sometimes inserts an extra 0 in the second rightmost position (1.2.4 becomes 1.2.0.4, 8.9.10.11.12 becomes 8.9.10.11.0.12 and so on).

CVS does a pretty good job at hiding these so called magic branches, but in a few places the hiding is incomplete:

• The magic branch number appears in the output from cvs log.
• You cannot specify a symbolic branch name to cvs admin.

You can use the admin command to reassign a symbolic name to a branch the way RCS expects it to be. If R4patches is assigned to the branch 1.4.2 (magic branch number 1.4.0.2) in file numbers.c you can do this:

$ cvs admin -NR4patches:1.4.2 numbers.c

It only works if at least one revision is already committed on the branch. Be very careful so that you do not assign the tag to the wrong number. (There is no way to see how the tag was assigned yesterday).