Yes, for the "S" argument, this is what the book says:

S: Measurement skip frequency (If the number has been already set in common variable #500, S = 0).

So, setting A & B isn't doing anything in program 9100? It should be the amount of approach and overrun at the time of measurement. In program 9300 (which is the centering program) it is using Local Variables #30 and #31. Also in program 9200 (inside diameter) uses #30 a bunch, but no #31.

The "F" and "R" are the measurement feed rate and rapid feed rate, which I'm not sure is doing anything (I am about to test it out on the machine). Wouldn't "F" be #9 and "R" be #18? If so, their values are allocated to #28 & #29 in program 9100...

Regarding the changes required in RED, are these lines supposed to be after the line they are on, or replacing that line, or ?

Thanks again for your help.