Wandering the anyXML rabbit warren, I came upon a new side passage which may be worth considering. This is to define in pure ODD a new attribute @exclude on the <content element, the effect of which is to specify one or more elements which should be excluded from said content model. We could implement this in DTD land (if we still did DTDs) with an exclusion exception; in Relaxng of course it has to be a schematron rule. It would enable us to do two things we currently do rather obscurely (1) prevent teix:egXML from containing teix:egXML (2) prevent <s> from containing <s>. And there may well be others. Unless anyone can plausibly show that this is bonkers, I will create a ticket.