> the problem is i have to address around 2000 different entity  
you don't need to tell me that there's loads of the little beasties, I
generate them all (wearing my other hat as editor of the mathml dtd:-)


> as far as i understand the pathes proposed there is not a statement  
> that can select *all* entity references at once...?

Why do you care if it is entered by an entity reference or just directly
as character data, or a character reference?

Why not just match on all one-character mo (which is virtually the same
as matching on all mo)

match="mml:mo[string-length(normalize-space(.))=1]"
or
match="mml:mo"

If you are using xslt2 you could match on all mo in certain ranges eg
match="mml:mo[matches(.,[ *[&#ff;-&x10ffff;] *]"

which mo do you _not_ want to add the attribute for, that is probably an
easier set of elements to match.

David