The result can be used to more correctly determine an Abbe offset error in {HEAD ~ the average position} of {TAIL ~ an off axis alignment mark}  
The result can be used to more correctly determine an Abbe offset error in { HEAD ~ the average position } of { TAIL ~ an off axis alignment mark }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH