Uche,

you wrote:
"
It's probably the use of "documents" above which prevented me from thinking of yours and Michael's documents in the same way.  As I understand Michael's quote, it's not just a convenient view ver existing documents, but fundamentally redesigning what "XML document" means, at least for this limited scenario.  Rather than documents I would think of the component bits as more like general entities or XInclude fragments.  In my opinion what Michael is proposing is in effect redesigning the fundamental behavior of an XML parser whereas what your super-documents idea is doing is layering some additional, useful capability on top of XML parsers as they already exist.
"

I have an inkling what you mean, although I am not sure about the significance of distinguishing documents from fragments.