In reply to Italics & Punctuation:
but its use there is just an abuse (it is (ab)used for positioning sub/superscripts, a left over from TeX which did so to maintain a compact font format in the olden days of tight computing resources).
Agreed. Its implementation is a bit odd, and in relation to math kerning and the existence of unique math italic characters, somewhat redundant. Its application to integrals is another issue. Alas, it was pretty much a done deal by the time we got involved in building the first (OpenType) math font.