Knock sum per cylinder sounds good, is that firing order sequence or actual crank position though?
I believe it's actual crank position - the two most active cylinders are 2 and 4, which makes sense.
I suspected it was gear related(Scoobyrom is good for that) and the 250 Right column sort of gave it away. It should also have a connection to the DBW RT Base (RPM) table I think which is consistent with it being referenced later on I suspect.
Essentially, this table should alter throttle angle closing decay rate based on boost in each gear
I'll see if I can dig out any further references when I get a chance - it's a long routine with mostly indirect references all the way through.