Siemens 802D G83

I purchased a used Romi C420 lathe (2011 model) with a 802d sl controller. I have a few operational questions that I would surely appreciate any answer to. The first question concerns a unexpected Z move at the start of a G83 drill operation:


The code listed below works almost as expected but, after line N90 the drill is 0.2 inches away from the part in Z. Then Z moves to +1.400 Why does it make this move?

N10 G291

N20 G20 G40 G90 G95

N30 T00

N40 G54 G0

N60 T0101 ; 9/16 DRILL

N65 G54

N70 G97 S600 M3

N90 G0 X0 Z0.2

N100 G83 Z-1.5 Q1500 R0.2 F0.005

N110 G80


The second question is: where do I find explanations for the ZSFR and ZSFI variables?

Thanks Much.