The Add All and Add Rest buttons on the Edit Variable dialog provide shortcuts for some common tasks:
Click Add All to use all possible values in one or multiple groupings. On the next dialog, choose whether to create a separate grouping for each value, or one grouping for all values combined.
If you have defined groupings for specific purposes and essentially want to create an "other" category for values not yet used, click Add Rest. Again you will have the choice to create individual groupings or one grouping with all remaining values combined.
When creating separate groupings for each value, you may choose to use the underlying data values rather than labels for the grouping names by marking the check box.