Use this field to specify the variables from the input data set by which to merge with the filter data set specified using the Data Set to Use for Filter field.If this field is left blank, these merge variables are assumed to be the same as the key merge variables specified for the filter data set.All of the variables in the input data set are displayed in the Available Variables field.
Highlight one or more variables. To highlight multiple variables at once, hold down while left-clicking on them.
Click to add the highlighted variable(s) to the Variables By Which to Merge Filter Data Set field.