Subroutines in myCNC are done in a manner similar to other industrial CNC systems.

Sample code of a G-code program containing subroutines #100 and #101:

G90 G0 Z10  F500
#100=[10]
#101=[10]
G0 X#100 Y#101
M98 P101 L5
M2
O100
G0 X#100Y#101
G1Z0
G2 X#100 Y#101 I10
#100=[#100+40]
G0 Z10
M99
O101
M98 P100 L5
#100=[10]
#101=[#101+40]
M99

The resultant program will look the following way: