Huh. TFM appears to be wrong. Well, that's not to say I know what Mach3's doing, but whatever it is doing, it's not doing what it's supposed to be doing.
I went into Settings and found the A-axis "diameter" was indeed 0.00in. Hmm. So how could it in any way calculate feedrate for any rotational movement combined with XYZ motion as per 10.1.6? Good question right there. Maybe it reverts to "feedrate" meaning RPM like it means when you're doing A-moves for an axis and integrates it with XYZ speed... how? Checked in General Config, yes it does have "A-axis is Angular" checked.
Well, next experiment was to change the A-axis diameter to 2.5in, which is close to what a lot of the workpiece will be. OK, but how do we even know what effect that had? There is no way to get Mach3 to read out what it chose for an A-rotation-rate. It gives a Feedrate but since it's unclear what that is even supposed to mean then that's useless. Well, since this code is like 90% rotational milling, my best shot was to go to ToolPath and Simulate Program Run to see how long the code takes.
And... it takes the exact same amount of time. Hmm, well maybe that's not strange, since the code normally provides a very large Feedrate (6000) in its rotational moves with the idea that the Motor Tuning on the A-axis would limit it to a fixed RPM. So, let's give it an absurdly large 1000 in diameter! That would mean 6000ipm surface speed would limit it 1.829 rpm.
But, it had NO effect. Again, exact same 3:31 runtime. So it's not using the A-diameter field at all (and the whole A-diameter concept was wrong from the start anyways!) I officially have no idea what Mach3 thinks it's using for a Feedrate for a rotational axis. It's not what's in the manual, that's for sure.