Payment Special Handling Codes

I would love to hear if anyone is using fields on AP invoices or payments to indicate special handling for a payment (other than using a DFF).

I support a Release 12 (12.0.6) system.  Our team will be creating a custom concurrent program to create a electronic payment file for check printing in a 3rd party system (similiar to an EDI 820 transaction).  That output file requires a 2 character Special Handling code.  The value for the code should ideally be selected at invoice entry.

Examples of these codes include: 'MU' to use U.S. mail to deliver the check; 'CU' to use Canadian mail to mail the check; 'OS' to overnight the check to the supplier; 'OP' to overnight the check to the payee (us).