Hello Ian,
Our systems give you some copy/paste possibilities, such as:
Duplicate record - if you want to copy paste from one puchase order to another, perhaps it's going to be easier just to duplicate the existing PO and remove unwanted lines.
Copy from spreadsheet or txt file and paste to record matrix section.
If the PO data is needed outside of the system, you can export the particular PO to a text file with Integration module>>Exports>>Purchase Order rows feature.
Best regards,
HansaWorld