If the display rule that you want to use is not available from the Rules window, you can add a new one. The new rule will be available for any of the Display Windows (Analysis, Full Record, Record Export, or Record List).
If you want to display both subfield a and subfield b, enter $a$b in the Extraction Template.
If you want to display the entire field, then choose “Extract the entire field” for the “Extract data in the following way” pane.
If you want to extract data from a fixed field, choose the extract data method “Extract a range of characters” and then choose the fixed field tag and the position of the characters you want to display.
You can now select the new rule for any of your display Window by highlighting the desired window first and then selecting the new rule and clicking on Include Rule.