Merging
Branches
It is often useful for multiple developers to work simultaneously on
different branches of a file. CVS allows this by default; for RCS, it
is possible if you create multiple source directories. Each source
directory should have a link named `RCS' which points to a common
directory of RCS master files. Then each source directory can have its
own choice of selected versions, but all share the same common RCS
records.
This technique works reliably and automatically, provided that the source files contain RCS version headers (see Version Headers). The headers enable Emacs to be sure, at all times, which version number is present in the work file.
If the files do not have version headers, you must instead tell Emacs explicitly in each session which branch you are working on. To do this, first find the file, then type C-u C-x C-q and specify the correct branch number. This ensures that Emacs knows which branch it is using during this particular editing session.
Merging
Branches