To transmit a SITOR (NBDP) message "live" to a shore office, which sequence should be dialed by the GMDSS operator?

The correct answer involves understanding the structure of the SITOR (Selective Identification of Telex On Radio) message used in the Narrow Band Digital Communications Systems (NBDP) for maritime communications.

In this context, to send a "live" message to a shore office using SITOR, the operator must construct a message that adheres to specific formatting and protocols. The sequence to be dialed typically includes vital information such as the service code, the time and date, and an identification reference.

The chosen sequence correctly includes the required elements to facilitate the transmission effectively. Specifically, the format "DIRTLX051440344+" indicates a valid service and sequence for direct communication with the shore office. The "DIR" prefix denotes a direct routing message, while "TLX" refers to telex messaging functionality. The subsequent digits represent a message identifier in an appropriate format, including the time, which is critical for establishing the context of the communication.

Understanding the nuances of this sequence is crucial. This pertains to the established communication protocols that govern effective transmission of messages over maritime channels to ensure that messages are sent accurately and are understandable by the receiving party. Different options represent variations that either do not conform to the correct format or include invalid identifiers, which could