Abstract: Online commerce is often conducted in a network including buyer computers, seller computers, financial institution computers and a payment management computer, which provides payment management services to sellers. Payment management software makes use of a generic framework including Payment Instruction, Capture, Refund, Account and Batch data structures. The generic framework is extended to support transactions which conform to uncommon payment protocols, for example, by shipping the merchandise Collect On Delivery or COD. The Payment Instruction data structure is modified to include two seller-definable fields, each of which can be written with data required for the particular type of transaction being modeled. The Account data structure is modified to include a field for receiving data identifying the particular type of transaction being modeled..