No session is required to send a message. The message is delivered according to the capabilities of the underlying network. No response is sent by the receiver and no retry is performed by the sender. The message arrives at the receiver any number of times, including not at all. The sender: MUST send a PUBWOS packet. The receiver: MAY decide to accept ownership of the message when it receives a PUBWOS packet. MUST treat any accepted messages as QoS 0. Informative: PUBWOS packets may be broadcast or unicast.