3.1.5.2 MS-Author-Via Response Header
A WebDAV client MAY send an OPTIONS request to the server and query the response headers for the presence of the MS-Author-Via header. The WebDAV client SHOULD use the following information to determine the best method to send requests to the server:
The WebDAV client SHOULD NOT use WebDAV commands when communicating with a server that responds to the OPTIONS command with only the MS-Author-Via: MS-FP/4.0 response header.
The WebDAV client MAY use WebDAV commands when communicating with a server that responds to the OPTIONS command with any of the following MS-Author-Via response header values:
MS-Author-Via: DAV
MS-Author-Via: DAV, MS-FP/4.0
MS-Author-Via: MS-FP/4.0, DAV
MS-Author-Via: MS-FP
MS-Author-Via: Token,DAV