Calling Zmacs from Lisp

[WJL@ZERMATT.lcs.mit.edu (Bill Long)]

Does anyone know how to invoke more general calls to "ed" or the
equivalent of a tag search from outside of Zmacs?  I have a knowledge
base file with forms that look like:

(defnode foo ...)

(defnode (foo bar) ...)

I can quickly go to edit the first kind with (ed 'foo), however, there
doesn't seem to be any way to get to the second kind from outside of
Zmacs.  On the other hand, it's clear that "ed" is more clever than the
documentation lets on.  I would gladly tell it what buffer to go to and
give it a string to search for if it could handle such things.  Barring
that, perhaps there's a way to call Tag Search from outside Zmacs.
Any ideas?
-Bill Long