range-time over flag.
interlace odd/even flag (always active)
interrupts (VERY coarse)

byuu might have ?anomie's? commented disassembly of it. I think that got left behind on my PC upgrade. It's not terribly useful anyway. You have to pass most of them just to get decent game compatibility, and the interlace flag is literally "opposite of whatever it was before" to pass. Not sure we know the initial state of the flag, though.

RTO is the big one, and anomie's documents ought to cover it all.