{TAIL ~ a reference plane} setting {HEAD ~ section} for setting a virtual reference plane as a reference defining a geometric placement of an arc welding torch relative to a workpiece during a welding operation, based on said plurality of position and orientation data obtained in said data obtaining section 
{ TAIL ~ a reference plane } setting { HEAD ~ section } for setting a virtual reference plane as a reference defining a geometric placement of an arc welding torch relative to a workpiece during a welding operation , based on said plurality of position and orientation data obtained in said data obtaining section
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH