Each arc and nonarc variable in an NPSC, or each variable in an LP, that has data in the CONDATA= data set must have a unique name. This variable is identified in the ARCDATA= data set. The NAME list variable must have character values (see the NAMECTRL= option in the PROC INTPOINT statement for more information). It is not necessary to have a NAME statement if the name of this SAS variable is _NAME_.