Scott, my interpretation, especially working wit MD, is that ovals are actually mirrored ellipses. . When I spec. its always major/minor axis with a c/l. This works for my job but not the standard your looking for. I give the little gray cells a chance to work on it.
Magistraeo, did you check with BOCA, the building code standards bible? I'm pretty sure most libraries have or can find you a copy. My copys at home or I'd quote a paragraph or 2 for you.