1.8 Vendor-Extensible Fields
As specified in section 2, the Active Directory Federation Services (AD FS) Proxy Protocol uses SOAP messages for communication, as specified in [SOAP1.1] and [SOAP1.2-1/2007]. The core functionality of SOAP is to provide extensibility. [SOAP1.2-1/2007] and [SOAP1.1] contains detailed discussion on SOAP messaging framework extensibility model. Vendors may use these SOAP extensibility points as specified.