Section: 4.2.1.3 Piggybacked Messages
Content: A piggybacked initial message is carried as a concatenation after a triggered response message and they share a common UDP header (see Figure 4.2.0-2). The UDP Destination port for the IP packet containing both the triggered response message and the piggybacked initial message shall be the same as the port number used for the triggered response message. The UDP Source port for the IP packet containing both the triggered response message and the piggybacked initial message shall be the same as the port number used for the triggered response message.