Re: semantics

Yes, Ron, that is correct: I expect most semantic markup to be added
either by an application when it is generating output or in cooperation
with a type-smart editor that allows annotations to the math it generates.
For example, it would not be unreasonable for a template-based math
editor to ask you about the types of the elements when you ask to
create a 3x3 matrix. Of course, one such valid type, probably the
default, is "General Expression."

Another point where we might want to allow type annotation is when
we are talking about floats. I know this can be a hornet's nest, but
there are times when you really want to be able to state that something
is an IEEE double float as opposed to something with arbitrary