CLASS variable <(options)> <variable <(options)>> </ global-options>;
The CLASS statement names the classification variables to be used as explanatory variables in the analysis. The CLASS statement must precede the MODEL statement. You can list the response variable for binary models in the CLASS statement, but this is not necessary.
The CLASS statement is documented in the section CLASS Statement in SAS/STAT 14.1 User's Guide: High-Performance Procedures.