%
( A simple O sub example )

F40
G90 G0 X0 Y0 Z0.25
M98 P1 L3
M30

O1
G91 G0 X1                ; Jog 1" along X (relative)
G90 G99 G81 Z-1.0 R0.25  ; Drill to Z-1.0
M99
%