In FE database view, while adding an invoice, if I need a new Transaction Code I can enter it on the fly in the appropriate field. The system will ask if I want to add the code and I say yes, or no if applicable. This is a much faster method of adding new codes rather than having to first of all get out of the invoice that needs the new code, find where new codes are added (which is not the way I was given by Support), then add the new code(s) there. Then go back to my invoice and add the code to the invoice.
I was coming to suggest this as well.