3.1.5.1.2 Extensions to PUT
File system clients might need to update file properties along with the contents of the file.
An X-MSDAVEXT: PROPPATCH header in the request instructs the server that the properties of the file are included in the body together with the content of the file, and are to be updated together.
This header SHOULD be included only on PUT commands that are targeted to servers that support the extensions, as advertised by an X-MSDAVEXT: 1 header in the OPTIONS command response from the server.<15>
The Content-Type: multipart/MSDAVEXTPrefixEncoded header MUST be added by the client on the request, and the body SHOULD be of the format specified in section 2.2.5.