The ID statement specifies which variable to include for identification of the observations in the OUTNBHD= output data set. The ID statement variable is also used for the labels and tool tips in the OBSERVATIONS plot and the tool tips in the PREDICTION plot.
In the KRIGE2D procedure you can specify only one ID variable in the ID statement. If no ID statement is given, then PROC KRIGE2D uses the observation number in the data sets and the plots.