GE Fanuc Series 15 i/150 i – Model A Connection Manual Vol 1
When parallel axis control, synchronization control, or tandem control is used, the same axis name can be assigned to multiple axes. In this case, a suffix like Xm or Xs can be assigned so that each axis can be identified for current position display and alarm indication. Parameter No. 1021 is used to assign a suffix to an axis name.