It was 20/40/80 at least dated back to 2005... It was the time when I used to fly TPE HKG weekly and accumulated 100+ sectors a year with >90% on cheap(est) economy tickets (plus 1 or 2 long haul Europe trips on J). At that time issuing a V class return ticket from Taiwan was only around NTD 5000-5500.

And before CX changed the rules, even my V class ticket was entitled to 24-hour guarantee seat without change penalty fee - it helped me a lot to make last minute changes.