In plain dress messages, which format line, besides 2,4,5,6,7,8,11,12,13,15, is mandatory?

• A. Line 9
• B. Line 10
• C. Line 14
• D. Line 16

Answer: (D)

In plain dress message formatting, there is a fixed set of lines that must appear to ensure the message can be read and processed reliably. The last format line is required because it serves as the definitive closing element of the message. This final line guarantees a clear end to the message, helps confirm the complete set of information has been transmitted, and often carries essential closing or routing details that readers and automated systems rely on to finalize handling, archiving, or forwarding the message. Without this concluding line, there can be ambiguity about where the message ends or who should process it, which can lead to delays or misrouting.

The other lines you’ve listed as mandatory cover the core header and routing information, so they’re essential for proper identification and delivery. The final line complements them by providing the definitive end and any last-required closing data, ensuring the message is complete in both human and machine terms.