From Microsoft:

“WS-Policy will describe how senders and receivers can specify their requirements and capabilities.

WS-Policy will be fully extensible and will not place limits on the types of requirements and capabilities that may be described; however, the specification will likely identify several basic service attributes including privacy attributes, encoding formats, security token requirements, and supported algorithms.

This specification will define a generic SOAP policy format, which can support more than just security policies. This specification will also define a mechanism for attaching or associating service policies with SOAP messages.”

See WS-Policy Specification.