ay then choose,
    through the user interface of client B, whether version 2 or
    version 3 should be kept, or maybe the document should be reverted
    on the server to version 1, or a merged version 4 is needed. Client
    B may then make a request that puts the document to the version the
    user wishes; this time setting an &#39;If-Match: &#34;2&#34;&#39; header instead.

    Both client A and client B would periodically poll the root
    folder of each scope they have access to, to see if the versi