Use this field to specify variables that are to be retained in the output data set or are to be used to merge the results of this process with the Annotation SAS Data Set specified subsequently. In the latter case, the values of these variables create a matching key used to perform the join. They are often the same as one or more of the By Variables specified previously.All of the variables in the specified input data set are displayed in the Available Variables field.
Highlight the variables to be used to key the merge. To highlight multiple variables at once, hold down while left-clicking on them.
Click to add the highlighted variable(s) to the Variables to Keep in Output or By Which to Merge Annotation Data field, as shown below: