Hans Aberg writes:
 > I think it would be unwise to impose any kind of restrictions onto
 > the math characters in the default settings: If they appears as
 > distinct entities, one is free to use them as that.

I have to agree with Hans on this one.  Typesetting math the way it is
done in TeX _is_ visual mark-up, while (most of) the textual mark-up
in LaTeX is logical mark-up.

So a distinct MICR will not gain anything (and probably cause multiple
problems) unless we support full logical mark-up.  However, this is
really a red herring.  IMHO it will render LaTeX basically unusable
for tasks it currently excels in (communication between human (!)
mathematicians), and not add anything to areas where logical markup is
required (because LaTeX would not be able to use most of the
additional information anyway).

This leaves two issues:

- Mapping Unicode into the current TeX (plus AMS-fonts etc.) naming
  scheme, so that people will eventually be able to use a Unicode
  enabled editor for their source files.  Since people from the AMS
  (and other math publishers?) have been working on the Unicode math
  planes, I assume that this is essentially understood.

- "Lost character conditions":  If a font does not provide all
  variations of a symbol that TeX or Unicode define, it should not
  quietly resort to a many-to-one mapping, i.e., at least a warning
  must be issued.  This also seems fairly natural.

Marcel