Credit transfer protocols are being designed and implemented in market-based resource allocation infrastructures. The design details of these protocols determine the access-control policies that can be expressed and the trading patterns that can be supported. A protocol that enables fine grained manipulation of ownership authorities can support a wider range of access policies and trading patterns than proposed designs, while reducing implementation complexity. Meeting the challenges of a market-based resource allocation infrastructure may yield a credit transfer protocol that is applicable in other domains. Notes: 15 Pages