I've made a number of changes to the schema to tighten up our markup practices:

• The four elements of the teiHeader are now mandatory (fileDesc, profileDesc, encodingDesc, and revisionDesc), and must be supplied in that order.
• profileDesc must contain textClass with at least one catRef in it.
• catRef/@target values are now constrained by the schema to conform with the list in our taxonomy. The schema will suggest the values and provide explanations of them.

I've updated hundreds of documents to make them conform with the new restrictions.