Outright egregious errors in the documentation, I'd say.
> On the specification page for an element is a field labeled "May
> contain". The value of the field is sometimes "Empty element".
> <ptr> is an empty element. That makes sense.
> But so too is <gi> and <datatype>, even though neither is, in XML's
> defined use of the term, an "empty element."
> Is "empty element" an idiosyncratic TEI term, meaning, I guess,
> "empty of further TEI elements"? Or is its appearance in, say, <gi>
> and <datatype> bugs in the documentation?