This command is used to cancel Canned Cycles such as G73, G81, G82 & G83.
N10 G99 G73 X10 Y10 Z-8 R2 Q1 F100N20 X20N30 G80
The first line moves the X & Y axis to 10mm position with retract plane set to 2mm, drilling to Z -8mm, peck of 1mm at 100 mm/minute feedrate and starts drilling.
The second line moves X axis to 20mm position and drill a hole as per the same values.
The third line cancels the G73 canned cycle.