Siemens SINUMERIK 840D Function Manual page 485

Extract from part program:
Program code
EGDEF(C,B,1,Z,1,Y,1)
EGON(C,"FINE",B,z0,z2,Z,udz,z2,Y,udy,z2)
...
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
M3: Coupled axes
14.4 Electronic gear (EG)
Comment
; Definition of EG axis grouping
with setpoint coupling (1) from
B, Z, Y to C (following axis).
; Activate coupling.
485