Comment #8 on issue 2913 by [email protected]: Patch: Implement session-terminate in lily.scm
http://code.google.com/p/lilypond/issues/detail?id=2913
"a user cannot define new bar lines if the alist containing them is not public, IIUC?"
A user cannot mess with the alist himself, but public functions defined in the same file as the alist may.
