Use sx -x lower (sgml2xml in Debian). -x lower is required since the XML DocBook uses all lowercase for its identifiers.
You should insert the appropriate document type declaration for the DocBook XML DTD you are using with a system identifier pointing to a locally-installed copy of the DTD. Unfortunately this must be done manually. This isn't required in all cases, but is often needed for declaring ID attributes and the ISO entities.
It is probably a bug in docbook2X. Please first validate your document to make sure the problem is not caused by markup errors. If the document is correct, please report the problem.
In your problem, please include the document which causes docbook2X to fail, or a pointer to it. You can also mail me snippets of the markup, but actually that is more cumbersome because I cannot reproduce the problem easily and the problem may be caused by something up the processing chain. Besides, I always would like more real testcases :)
For the tools based on XML::DOM::Map, it would also be helpful to include a stack trace which is displayed after the tool “crashes” when running under Perl debug mode (use perl -d).
Of course. But if your changes are application-specific (i.e. depends on your peculiar markup), please generalize them.
Patches that eliminate items on the todo list would be the most helpful.