[jdom-interest] Internal DTD subset verification

[Alex Rosen]

Interestingly, DOM takes a limited verification approach. It's defined to
throw exceptions for invalid names (e.g. element or attribute names) but not
for illegal characters in data (e.g. attribute values or text nodes). I'm
pretty sure that it doesn't check most of the other non-trivial WF
constraints. That argues against extensive WF checking everywhere being the
"spirit of XML".

(It looks like dom4j doesn't check anything.)

Alex