Invoices are printed only after data has been written to disk to assure that every printed document has valid electronic data associated with it. To make the actual invoice form adaptable for different customer requirements the invoice printing process is broken into two separate components. The first of these components is the software that selects the appropriate invoice(s) to print. This program determines which invoice needs to be printed and then invokes the actual invoice print routine, passing it the invoice number to print. This allows the user interface portion of invoice printing to be the same at all sites while the actual print routine can be modified as required.
Invoice print routines are normally named PINVxxxx where the xxxx section of the name is the unique identifier of the specific format.