Did further work on the ODD file to add all the values proposed for different document types in the taxonomy here. The taxonomy itself needs to be updated, though; it assumes that the document type will be specified through a <classCode> tag, as was the case with the P4 projects, but I've decided to go with the @rend on the root tag instead, because a) it's actually a categorization which is made solely for the purposes of output rendering, and b) using an attribute list allows me to force its presence and restrict its values in a way that's helpful to encoders.