A purchase order is normally associated with multiple other documents, like a Statement of Work, Contracts, Requisitions, Quotes, Invoices, Payments, etc.
And these documents are needed while the PO is active, and even after is completed for review purposes.
Our TitaniumGP customer, uses the Attachment functionality to affix quotes and SOW’s right in their PO’s or Payables transactions then use these documents to be able to code invoices appropriately.
This also provides the ability to department managers to be able to approve the payment of an invoice by having in one location all documents readily available to assist in understanding the invoice received.
Then, these same documents become available in historical mode and can be used for budgetary purposes.