[relax-ng-comment] Inter schema references.

[Peter Wilson <PWILSON@GORGE.NET>]

More and more documents are being composed from multiple schemas (e.g.
xhtml + smil). I now have a Mozilla Javascript validator working
(mostly) and am now addressing issues where schemas reference one
another. I would like to cache schemas and just reference them where
needed. Some schemas are quite large (xhtml, xul, docbook) and it should
not be necessary to reload a schema if it is already loaded. Both ways
that RelaxNg refers to nested schemas (externalRef or include) just use
file names. This makes it hard to detect when you are indeed referencing
a complete external schema.  Some sort of symbolic reference based on
the URI of the schema and possibly a start pattern would address the
problem. Could a uri attribute on the include pattern be an alternative
to the href attribute and let the schema processor determine the
location (file or cache). Any ideas?