I don't have a lot of experience with copying records (or NetSuite in general for that matter), but I thought potentially I may want to run this script on copy as well. Since it's mean to update the line item tax codes when the shipaddress changes, potentially a user may copy a PO and change the shipaddress. But that's a good suggestion, I should explicitly define which user event types I want it to run on rather than just a blanket 'if user is not creating'. Thanks