Re: content mark-up: operators vs. relations?
> It is an error to enclose a relation in an element other than reln.
> But the example immediately following and some earlier examples show relns
> inside applys.
but a `reln' is not a `relation element' according to the text of the
spec. So you are supposed to use <reln/> to apply <lt/> to two values, but
if you want to combine two such relations with <and/> then you need to
The plan is that this situation will be improved in MathML2, although
the details are not finalised.
The current best guess is that the restriction on not using <apply/>
with `relation' elements will be dropped and so you will be able to
uniformly use <apply/> (with reln being kept for largely historical