User exit record lock concern

I am trying to update a user field keyed to P.O. Item (a user defined secondary 
object to those who speak Integrator) when a P.O. is closed.  I could do an 
update from sql in one of the P.O. user exits, but I am worried about record 
locks.  Since mapics updates the status code in P.O. items when a P.O. is 
closed, does anyone know if there are provisions for record locks in that logic 
i.e. does the maintenance get deffered to a later time if one of the effected 
records is active?  If so, is there a way to apply those provisions to user 
exit code?

In general, what is the best approach to this problem?  We have SystemLink, so 
we could conceivably couch these updates in a SystemLink request.  Would that 
solve the record lock issue, or would the SystemLink request fail too if one of 
the records was active?

Thanks in advance

Josh Diggs
Information Systems Manager
California Fine Wire
(805) 489-5144