The CLASS statement names the classification variables to be used in the analysis. Classification variables can be either character or numeric. If a single response variable is specified in the MODEL statement, it must also be specified in a CLASS statement.

Class levels are determined from the formatted values of the CLASS variables. Thus, you can use formats to group values into levels. See the discussion of the FORMAT procedure in SAS Language Reference: Dictionary.

If the CLASS statement is used, it must appear before any of the MODEL statements.