An XML-based expression grammar for policies is described in the Web Services Policy Framework (WS-Policy) specification, published by the W3C. The specification also describes how a policy can be associated with a registry object.

The CentraSite UDDI registry supports WS-PolicyAttachment version 1.2 and 1.5. Policy attachments can be either WSDL-based or UDDI-based. Currently, CentraSite supports UDDI-based policy attachments. With UDDI-based policy attachments, the policies are modeled in the UDDI registry using UDDI elements.