From the textbook The New Old Sexuality: A Cross Cultural Look at Kink

Achieving orgasm through pain has several phases shown as wave-like peaks in this image. The phases are known as the Western Pain (WP), Trough of Shift (ToS), Western Orgasm (WO), Refractory Trough (RT), Eastern Pain (EP), Trough of Ascendance (TA), and Eastern Orgasm (EO, also known colloquially as the And-gasm). Research into new phases tentatively called the Northern Orgasm (or exclusive or-gasm) is ongoing but requires pain beyond what stupid Donna on the ethics committee is willing to approve.