FYI for anyone finding this in Google Search… I stumbled upon this RDF vocabulary which seems to have replicated at least some of the basic semantic structural elements that TEI provides for documents.
It appears to be a standard related to digital books for disabled users.
If you are simply looking for some standard-defined metadata elements to mix in to an Omeka-S resource template, this might do the trick for you rather than creating a custom vocabulary/field/element.