Section 4.4.3. C'mon Peter, this was one of the things we spent immense
time hashing out well over a year ago. Now it turns out that de facto,
typical real-world NVPs will actually on demand read external entities...
but it was a basic design assumption, driven mostly by the war-stories
of the browser guys, that it was not reasonable to expect a lightweight
web-client type of app to resolve external entities in real time.
The expectation is that the *right* way to do this kind of thing is
with XLink, which should have been done months ago if it hadn't been
for this #%!%$@ namespace swamp. -Tim