Is Maclisp .MCL or .LSP?

[MACRAKIS at USC-ISIE]

The Twenex Tags program assumes that programs with a second file name of LSP
are Interlisp, and that those with one of MCL are Maclisp.  Emacs, however,
only goes into Lisp mode with the LSP filename.  (Won't Emacs Lisp mode be
about right for Interlisp, anyway?)  Maclisp uses a default second file name of
LSP.  Can Tags, Emacs, and Maclisp be brought into agreement on this?  I would
prefer LSP, but I suppose there are large bodies of Interlisp programmers ready
to rebel, so MCL will do as long as it's applied consistently.