CLASS Statement
CLASS variables ;

The CLASS statement names variables to be analyzed as categorical variables. For categorical variables, PROC SURVEYMEANS  estimates the proportion in each category or level, instead of the overall mean. PROC SURVEYMEANS  always analyzes character variables as categorical. If you want categorical analysis for a numeric variable, you must include that variable in the CLASS statement.

The CLASS variables are one or more variables in the DATA= input data set. These variables can be either character or numeric. The formatted values of the CLASS variables determine the categorical variable levels. Thus, you can use formats to group values into levels. See the FORMAT procedure in the Base SAS Procedures Guide and the FORMAT statement and SAS formats in SAS Formats and Informats: Reference for more information.

When determining levels of a CLASS variable, an observation with missing values for this CLASS variable is excluded, unless you specify the MISSING option. For more information, see the section Missing Values.

You can use multiple CLASS statements to specify categorical variables.

When you specify classification variables, you can use the SAS system option SUMSIZE= to limit (or to specify) the amount of memory that is available for data analysis. See the chapter on SAS system options in SAS System Options: Reference for a description of the SUMSIZE= option.