You can specify a label of up to 40 characters for the horizontal axis by assigning the label to the subgroup variable with a LABEL statement (refer to SAS Statements: Reference for a description of LABEL statements). If you use a LABEL statement after the PROC SHEWHART statement and before the RUN statement, the label is associated with the variable only for the duration of the PROC step.

For an example, see Labeling the Vertical Axis, where Figure 17.172 redisplays the and s charts in Figure 17.171 with specified horizontal and vertical axis labels.