The COST statement identifies the SAS variable in the ARCDATA= data set that contains the per unit flow cost through an arc. If an observation contains nonarc variable information, the value of the COST list variable is the objective function coefficient of the nonarc variable named in the NAME list variable in that observation. The COST list variable must have numeric values. It is not necessary to specify a COST statement if the name of the SAS variable is _COST_ or _LENGTH_.