Restrict authority to printer spool files

Question: I need to be able to restrict authority to spool files by plant. I have been directed to user exit EXIT_SAPLSPOR_001 as a solution to the problem. This also involves adding an entry to table TSPOPTIONS with a parameter of AUTHORITY and a value of CUSTOM.
Does anybody know how to use this user exit or know another method I can use.
Thanks in anticipation.
Steve.

Answer:
Your user exit will do no good. There is no PLANT field to check. Your control is on the authorization the USER places on the spool output. If the user enters a value representing a PLANT then you can use the standard S_SPO_ACT to control the access based on the that value. The field is arbitrary and the user can place ANY value they want but must have access to that value in S_SPO_ACT.

The field is labled authorization in the second box on the Print screen List when you request output.