Which of the following is included in the format line of a message?

The inclusion of the Message ID in the format line of a message is essential for tracking and identification purposes. The Message ID serves as a unique identifier for each message, allowing both the sender and receiver to reference that specific communication easily. This is particularly important in environments where multiple messages may be exchanged or stored, as it helps to distinguish each message from others.

The Message ID can facilitate searching, archiving, and retrieving messages, especially in systems where messages are sorted or categorized. Its presence in the format line ensures that critical information about the message's origin and purpose is easily accessible and traceable.

In contrast, elements such as the Sender's Address, Ending Sign, and Footer Information typically pertain to other structural aspects of the message rather than being a mandated component of the format line. The Sender's Address, for instance, is often included to inform recipients of where the message originates but not necessarily as part of the format line itself.