DOCBOOK-APPS: sgml-parent-document equivalent in XMetaL?

[David Cramer <david_cramer at broadjump dot com>]

Hi there,
Some of my fellow writers use XMetaL and would like to know if there's
an XMetaL equivalent of:

<!-- Keep this at the end -->
<!-- Local Variables: -->
<!-- sgml-parent-document: "../wrapper.xml" -->
<!-- End: -->

Apparently when they switch between plain text view and the other views
while editing a document fragment, XMetaL panics and makes them navigate
to a dtd every single time. 

I know XMetaL has some degree of programmability. Perhaps someone has
written some nice addons for it?

Thanks,
David