Changing part of a variable field.

["McClellan Jr., Michael C." <MMcClellan@xxxxxxxxxx>]

We are in a metropolitan area that is going to add new area codes this
summer.  I'm working on a method to easily change the area codes of our
current patrons which is stored as part of the (t) variable field i.e.
612-630-6042.  Of course you can't use the Rapid Update program to
replace part of a variable field.  So I was wondering if the following
method would work:  If we were to build a file of patron records with
the old area code and then import them into a word processing or other
program where we could search and replace just the area code and then ?
use the  P > Load MARC PATRON records from tape or FTS to reload them
back into the database?  

I recall seeing posts from academic libraries where loading patron
records from another source happens periodically.  Can you overlay
existing records with new ones?  I also assume you have to do this
during a period in which there would be no activity on the record.  I
would appreciate any comments on this problem.  It would be much easier
if there was a way to replace just part of a variable field in a rapid
update.

Mike McClellan
Minneapolis Public Library
300 Nicollet Mall
Minneapolis, MN   55401
612-630-6042
mmcclellan@xxxxxxxxxx