Well, that's it, but where do you stop? What I must understand to do what I want with a document has nothing to do with what you must understand to do what you want. And perhaps neither of us have purposes that were foreseen by the publisher.
True, so it would perhaps be a requirement of any adaptation of the MCE pattern
for XML invoices (and other business documents like them) that the MCE-esque
attributes be customisable. Not too easy for an attribute.
