Hi Jean,
All XIncludes are resolved by the parser before the DocBook stylesheet sees
the content. I think these problems should be presented to the libxml2
mailing list.
Right away you pointed out one non-conformance issue: the XInclude
standard says a missing href attribute is supposed to be the same thing as
an href="" attribute, but your tests show they behave differently.
Bob Stayton
Sagehill Enterprises
DocBook Consulting
bobs@sagehill.net