126.96.36.199 Determining Server Capabilities
A prospective client MAY perform an HTTP OPTIONS request, as specified in [RFC2616] section 9.2, against a server to determine if it is a FrontPage Server Extensions: Website Management Protocol server.
When receiving an OPTIONS request, a FrontPage Server Extensions: Website Management Protocol server MUST return the header "MS-Author-Via:" with a value that includes "MS-FP/4.0" to indicate that the server supports the FrontPage Server Extensions: Website Management Protocol, as specified in [MS-WDVSE] section 188.8.131.52. The server SHOULD list the protocols in the MS-Author-Via header in order of preference from highest to lowest. The client SHOULD use the first client-supported protocol listed in the MS-Author-Via header. Results of the HTTP OPTIONS request that are returned from the server SHOULD be cached by clients as a performance optimization.