ID variables;
The ID statement names one or more variables for identifying observations in the output and in the plots. The statement requires an INPVALUES= data set. All ID variables are displayed in the "pValues" table. The ID variables are used as the X axis for the plots requested by the PLOTS=PBYTEST and PLOTS=MANHATTAN options in the PROC MULTTEST statement; they are also used to label points on the Manhattan plots. This option has no effect on the OUT= data set.