Original Sentence If the subscribing Client has been granted maximum QoS 0, then an Application Message originally published as QoS 2 might get lost on the hop to the Client, but the Server should never send a duplicate of that Message. A QoS 1 Message published to the same topic might either get lost or duplicated on its transmission to that Client. Changed Sentence If the subscribing Client has been granted a maximum QoS 0, then an Application Message originally published as QoS 2 or QoS1 might get lost on the hop to the Client, but the Server should never send a duplicate of that Message. ================================== Original Sentence MQTT delivers Application Messages according to the Quality of Service (QoS) levels defined here. The delivery protocol is symmetric, in the diagrams below the Client and Server can each take the role of either Sender or Receiver. In the case of the Client, "Deliver Application Message" means give the message to the application. In the case of the Server it means send a copy of the Message to each Client with a matching subscription. Changed Sentence MQTT delivers Application Messages according to the Quality of Service (QoS) levels defined here. The delivery protocol is symmetric, in the diagrams below the Client and Server can each take the role of either Sender or Receiver. In the case of the Client, "Deliver Application Message" means give the message to the application. In the case of the Server it means send a copy of the Message to each Client with a matching subscription. QoS levels are only applicable for a single hop between a Sender or Receiver and not for an end to end transmission.