Not necessarily Fanuc programming command.

RMX control on a TRAK CNC Machine and they list G06 / G07 Helix code using "Z", "K" & "D".
What they cannot seemingly supply is the rules for this Helix code that they say is standard.
None of my current Fanuc Programming manuals have this Helix code but list it as a "Spline" code.

Does anybody have a fact sheet for using this G06/G07 Helix code using format K-D-Z- variables?
Internet search has not produced anything.

Trak states "K" defines center point in "Z" for first revolution. TRAK says that is always zero? Makes only some sense.
What if your starting helix below zero absolute coordinate?
"D" defines the number of revolutions. Ok but what if you are not in complete revolutions? Do you divide?
D2 = 2 turns, D2.5 =2 turns? Then what of "Z" value in same line of code?
Their example only shows this: G06 X0. Y0. Z0. I0. J0. K0. D2.0

I appreciate any light you may be able to shed on this?