Just have to spend time and read on here.
OffT, yes, I know this is the VA side:
If they (QF) changes the equipment, ie, goes from a 330 to 737 with a smaller cabin, they would have to downgrade some.
Years ago, in the 2000s or so, QF had a lot of 767s flying between PER - east coast Aust, and also, even SYD - MEL and sometimes SYD - BNE, but these days, its more or less 737s.
Some people mention being downgraded, and they have to claim ORC (original routing credit), ie, to claim for the points and SC they paid for, but for which they have gotten an equipment change.
If you have paid a rev tix for a J cabin, and then you see that the plane at your gate is 737, instead of a 330, and that you are now down the back of the bus.
Of course, we all love an upgrade/op up, when they upgrade us without us asking, (I got it once with QF), downgrades do happen too.
Oh, and not forgetting being moved from mainline QF to budget JQ.
OnT.