Allow Subcontractor to reference their invoice number for a pay application

When submitting a pay application, we have subcontractors asking for a place for them to enter their ERP system's invoice number. When receiving payment from us, the payment references the invoice number/pay app number that is created by Trimble Pay. The subcontractor then needs to try to match our pay app number with what number their ERP system uses. A simple reference # field would be helpful for them during pay app submittal.