This implies, as I agree with, that a single-action pop-up or form (which does not progress) should have OK-Cancel, and that a progressive form should be Cancel

This implies, as I agree with, that a single-action pop-up or form (which does not progress) should have OK-Cancel, and that a progressive form should be Cancel-OK, as clicking OK progresses things to the "right" (or next "page"), whereas Cancel stops that progression.