Who uses a G07 Helix syntax like this?

I'm working on a post for our Southwestern Industries Trak Mill, and working post from another CAM system outputs a helix in this format.

N8 Z.1
N9 G01 X.1 F20.
N10 G07 X-.1 Z.05 I-.1 J0 K0. D.5
N11 G07 X.1 Z0 I.1 J0 K0. D.5
N12 G07 X-.1 Z-.05 I-.1 J0 K0. D.5
N13 G07 X.1 Z-.1 I.1 J0 K0. D.5
N14 G07 X-.1 Z-.15 I-.1 J0 K0. D.5
N15 G07 X.1 Z-.2 I.1 J0 K0. D.5
N16 G07 X-.1 Z-.25 I-.1 J0 K0. D.5
N17 G01 X0
N18 G41 D09 X-.0568 Y.0739
N19 G01 X-.1052 Y.0614
N20 G03 X-.1422 Y.0199 I.0125 J-.0484
N21 X-.1436 Y0 I.1422 J-.0199
N22 I.1436 J0
N23 X-.1422 Y-.0199 I.1436 J0
N24 X-.1052 Y-.0614 I.0495 J.0069
N25 G01 X-.0568 Y-.0739
N26 G01 X0 Y0
N27 G00 Z.1 M08
N28 Z1. M09
N29 M05

XYZ and IJK are used normally, but the D is represented as a factor of the degrees needed to make the arc. (D.5 = 180 degrees.)

Seems really strange, just not sure where I can get a syntax definition for this method and who's standard it is. Fanuc just uses XYZ and IJK with G2/3. They also have a G07 but it's syntax is still different than this.

Keep in mind that the Trak LPM controller is not a true Fanuc controller. It's Fanuc based, and has enough functionality to work, but there are limitations when programming off-line. You may have discovered one of them. I seem to recall trying to get G07 working in my post about 10 years ago and hitting roadblocks. Maybe I gave up too soon, but I never did get a solution. I just output p-2-p code for helixes for the Trak LPM.

Also you might want to keep this in the back of your mind. If you use arc motions (G2, G3) be aware that in the G19 plane the Trak LPM controller will reverse the direction of the arc. You will need to reverse the direction of the arc moves in the G19 plane in your CAM software if you can.