The VARCOMP Procedure

The CLASS statement specifies the classification variables to be used in the analysis. All effects in the MODEL statement must be composed of effects that appear in the CLASS statement. Classification variables can be either numeric or character; if they are character, only the first 16 characters are used.

Numeric classification variables are not restricted to integers since a variable’s format determines the levels. For more information, see the discussion of the FORMAT statement in SAS Language Reference: Dictionary.