Service Contract, even expressed in the form of a bunch of Policies, is an agree subset of the Service Description (in exceptional cases Service Contract may include Service Description in full, i.e. Service Description may be used as a Service Contract for such services as Security, Compliance, and alike) and combined with some policies that the consumer has brought to the table. Nonetheless, in essence, Service Contract is an agreed part of Service Description. For example, if Service Description contains definition of 2 public service interfaces - Web Servces and MOM Messaging - but the Service Contract with Consumer C mentions only MOM Messaging, the Consumer C has no rights to call the Web Service interface (though this interface is public too).