As one of the resident pensioners on this forum I'm not convinced my memory is at full capacity either, so welcome to a not very exclusive but well respected club. However unless I'm much mistaken, online transfers is the same as intraline transfers, within an aviation company; whereas offline is another way of saying "interline" transfers, across companies. The wording of intraline and interline causes a lot of problems despite their long heritage, hence in more recent times the move to use the phrase online and offline, the line being airline. It is certainly clearer for non native English speakers. But I'm pretty certain that MCT, in any version, can only occur with one or more tickets but within one PNR. If you have 2 PNRs you don't have MCT.