How to extend ^TO_

Hi,
in various places within my procmail recipes I have the following string:
(^TO_|Delivered-To:)

How can I define this as a variable that I can use repeatedly in my 
recipes and how do I include it in my recipes?
Thanks,
Geoff
____________________________________________________________
procmail mailing list   Procmail homepage: http://www.procmail.org/
procmail(_at_)lists(_dot_)RWTH-Aachen(_dot_)de
http://mailman.rwth-aachen.de/mailman/listinfo/procmail