3.1.5.6 Sending a RopPending ROP Response
The server SHOULD send a RopPending ROP response (section 2.2.1.3.4) to the client whenever there are pending notifications on the session context associated with the client and the RopNotify ROP response (section 2.2.1.4.1) for the associated notification does not fit in the response buffer. The server sends a RopPending ROP response to the client whenever there are pending notifications on any linked session contexts.