Tag all selected files by running ‘cvs tag’ on
them (cvs-mode-tag). It’s usually preferable to tag a directory
at a time. Rather than selecting all files (which too often doesn’t
select all files but only the few that are displayed), clear the
selection with M-DEL (cvs-mode-unmark-all-files), position
the cursor on the directory you want to tag and hit t.
By default, ‘tag’ commands ignore the marks. This can be changed
with cvs-invert-ignore-marks. Also, by default ‘tag’ can
only be applied to directories, see cvs-force-dir-tag if you want
to change this behavior.