Hans Aberg wrote:
>   The whole problem is more complicated, because it is not only a question
> of expansion, but also when things should be expanded: Sometimes
> immediately, sometimes later. The correct way around this would be to
> define a stricter input syntax which separates the elements authoring
> semantics, typesetting style elements and typesetting fine-tuning, but

This is basically what I was thinking of.  I couln't find an argument
for needing more than 2 tiers in the expansion process, but what I was
describing is certainly generalizable.  So precisely why do you think
one needs to distinguish "authoring semantics", "typesetting style" and

> there is no way to enforce such a syntax in TeX.

This is clear.  Question: how difficult would it be to extend TeX to
allow for dual/multiple tier expansion?  What are the draw-backs?