Mark, are you referring to the fact that the output starts with N## on each line?
Example:
N25 S15000 M3
N30 G54
N35 G0 X29.76 Y28.486
N40 G43 Z13.16 H31
N45 G0 Z1.016
N50 G1 X29.98 Z1.001 F1016
N55 X30.198 Y28.501 Z0.985
N60 X30.416 Y28.531 Z0.97
If so, the N## is just a sequence number, or line number, so that you can reference which line of Gcode is being run. It is optional and/or configurable.
In the onefinity post-processor, you customize this or disable it in the properties (see image)
