Formatting is often tied up with the values of attributes, but it is not possible to make a tagging declaration which refers to attributes. Would it make sense to expand the number of attributes on <tagUsage> to something in the manner of

	<tagUsage gi="p" att="type" att-value="intro" render="#p-intro">introductory paragraph</tagUsage>

One could then create a <rendition> which would operate not just on element level, but on element plus attribute level – one might even wish to allow leaving out the element (now mandatory) and style all elements with certain attribute values in a certain way.

The idea is to make it possible for a project to style individual documents (or a document corpus) in a TEI application without having to fiddle (too much) with the code.