Each table has a limit around 13,000 characters, that includes the standard Sage fields. I posted something earlier about the work table that I thought it had less characters available than the other tables, because I did not realize that the limit included the standard fields.
if you are adding these to the vendor master table and want to print them on the PO, you can link in the vendor master or you can add the UDFto the PO_PurchaseOrderWrk table. if you want to add it to the work table, check the available limit there first (and leave some extra for future fields :) )