This forum is to discuss different features/issues of Oracle Financials modules ( GL - General Ledger, AP - Accounts Payable, AR - Accounts Receivable, FA - Fixed Assets & CM - Cash Management ).
if this is very much required then you have to customize your Pay on receipt Standard Program. Categories you have to create in GL Document sequence region OU wise (can store OU in DFF) and then customize the program to pick category based on that OU.