Today I've implemented those components of the document type taxonomy that we've agreed on (there are still some questions to be dealt with around the categorization of various editorial documents). All documents now have at a <profileDesc> with a <textClass> containing at least one <catRef>, pointing to the taxonomy through the use of the mdt prefix, which is dereferenced to the boilerplate/includes.xml file.

I've also implemented support for this in the search page of the redesign, with five sample categories for testing purposes. This seems to be working well.