The purpose of the SSM working group is to define source-specific multicast in order to provide unambiguous semantics to the designers of the protocols and host interfaces used in conjunction with source-specific multicast. SSM is intended to be a short-lived and highly-focused working group. The working group has two specific tasks: 1) A concise standards-track RFC that clearly defines the source-specific multicast model and its relation to RFC 1112 multicast. This document will specify of the host interfaces to be used for source-specific multicast, the rules that hosts, routers, and protocols must follow when allocating and using source-specific addresses. This document will serve as a reference to RFC authors designing protocols and host interfaces that implement SSM. 2) An informational RFC providing an overview of source-specific multicast. This document will serve as a starting point for parties interested in source-specific multicast. Other SSM-related documents may be taken on as work items by other multicast working groups that have more specific expertise, including pim, mboned, and magma. For instance, a document describing the use of IGMPv3 for SSM has been adopted by MAGMA. The SSM working group chairs will cooperate with chairs of the related working groups and the Area Directors to determine the appropriate location of SSM-related documents that arise during the working group's lifetime.