🔍 Key Concepts

• ARQ (Automatic Repeat reQuest) procedures for ship-to-ship telex/RTTY traffic • The normal order of: call setup → identification/answer-back → message → termination • Meaning and use of WRU, AAB, KKKK, and selective calling (selcal)

💭 Think About

• In a manual ship-ship ARQ telex exchange, what has to happen before you are allowed to send the actual text of your message? • Which signals or commands are used to positively identify the other station and confirm the circuit is correctly established? • When and why is KKKK used in telex procedures, and does it come before or after the message body?

✅ Before You Answer

• Identify which option shows a clear call setup step appropriate for ship-to-ship, not coast station working. • Check which sequence shows the WRU–answer-back (AAB) exchange happening at a logical time for identification before message text. • Confirm that any termination signal (like KKKK) appears in the correct place in the sequence, not before identification or message transmission.