Hello www-math@w3.org,
I have a few questions regarding the following piece from the MathML 3.0 spec (section Uses of <domainofapplication>, <interval>, <condition>, <lowlimit> and <uplimit>)
The general technique of using a condition element together with domainofapplication is quite powerful. For example, to extend the previous example to a multivariate domain, one may use an extra bound variable and a domain of application corresponding to a cartesian product:


Note that the order of the inner and outer bound variables is significant.
My questions:
  1. Does this exaple try to denote a double integral ? If yes, is this the recommended way to do it ?
  2. Why is the <set> wrapper inside <domainofapplication> necessary at all? Only because the later happens to just take a single argument ?
    In a set, however, I could put arbitrary elements. From the example I conclude that this use of <set> is very specific to the <domainofapplication> parent and hence requires a very specific element list. I could not find any specification about the required structure of this <set>.
  3. What purpose serves the last <set> element <list>... ? We already have declared <bvar> t and u (in that order) as set element 1 and 2. Why list them again ? Does the final note of this section refer in any way to the use of the <list> element ?
Any comments or expalantions would be greatly appreciated.

Thank you in advance,