The SUMMARY Procedure

VAR Statement

Identifies the analysis variables and their order in the results.

Default:	If you omit the VAR statement, then PROC SUMMARY produces a simple count of observations, whereas PROC MEANS tries to analyze all the numeric variables that are not listed in the other statements.
Interaction:	If you specify statistics on the PROC SUMMARY statement and the VAR statement is omitted, then PROC SUMMARY stops processing and an error message is written to the SAS log.

Note: See the VAR Statement in PROC MEANS for a full description of the VAR statement. [cautionend]