Re: Mathematical accents

they are all correct (from the point of view of being valid mathml) 
but I think that, where the diacritic is being used as an operator that
could potentially be applied to more than just a single letter, using
mover with the non combining form is preferable (which is why all the
mathml entity names for accents expand to the non-combining form if at
all possible).

If you apply an operator to a base then (even if the rendering is the
same, or in some cases improved) if a pre-composed character is used
searching and other uses are far more consistent if the operator and
base are consistently marked up the same way for all combinations (even
if the file undergoes unicode normalisation) and this isn't the case
where combining characters are used. 

mathml does make use of a combining negation slash to make negated
operators, but there one (can at least) consider a negated operator such
as (not equals) as a distinct operator in its own right, rather than a
result of a higher order compositin of the original operator with a
negation.

Of course the above discussion relates to rendering/searching/other-user
visible stuff. Iff a system decides to use some precomposed glyphs from
a font to render certain mover combinations, that is up to the system.

David

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