Definition: The 'ver' attribute is a string that identifies a particular version of the roster information. The value MUST be generated only by the server and MUST be treated by the client as opaque. The server can use any appropriate method for generating the version ID, such as a hash of the roster data or a strictly-increasing sequence number.
If a client supports roster versioning and the server to which it has connected advertises support for roster versioning as described under Stream Feature, then the client MUST include the 'ver' element in its request for the roster. If the server does not advertise support for roster versioning, the client MUST NOT include the 'ver' attribute. If included, the 'ver' attribute is set to the version ID associated with its last cache of the roster.
+If a client supports roster versioning and the server to which it has connected advertises support for roster versioning as described under Stream Feature, then the client MUST include the 'ver' element in its request for the roster. If the server does not advertise support for roster versioning, the client MUST NOT include the 'ver' attribute. If the client includes the 'ver' attribute in its roster get, it sets the attribute's value to the version ID associated with its last cache of the roster.