18.104.22.168 Sending QM Notify Messages
Each Authenticated Internet Protocol peer MUST allow only one outstanding Notify message affiliated with a QM SA (section 22.214.171.124) at a time. The initiator MUST NOT send a Notify message until it has received a response to all previous messages. This behavior does not apply to Notify messages that do not have the Reliable message flag set, but MUST include Notify messages that have the Reliable message flag set.
If the sender of a Notify message generates one or multiple Notify messages while it waits for a response to a previously sent message, each message MUST be queued in the Request Non-notify Message pending Queue (section 3.1.1) until all preceding Notify messages are acknowledged (section 126.96.36.199). If there are no outstanding notifies the packet MUST be sent immediately.