*Question T1D03:
[97.211(b), 97.215(b), 97.113(a)(4)] When is it permissible to transmit messages encoded to obscure their meaning?*  

*Correct Answer is  C: Only when transmitting control commands to space stations or radio control craft*  

### AI Response: (may contain errors)  

To understand when it is permissible to transmit messages encoded to obscure their meaning, we need to refer to the relevant FCC rules.

### Correct Answer: C - Only when transmitting control commands to space stations or radio control craft

- **Explanation**: The FCC regulations allow for the encoding of messages to obscure their meaning specifically when controlling space stations or radio control craft. This is because these types of communications often require specific commands that may not be easily understood by unintended recipients, and the nature of the operation justifies the use of encoded messages.

### Why the Other Choices are Incorrect:

- **A: Only during contests**  
  - **Explanation**: While contests may have specific rules regarding communication, they do not permit the use of encoded messages to obscure meaning. All communications must be clear and understandable to ensure fair competition.

- **B: Only when transmitting certain approved digital codes**  
  - **Explanation**: The use of certain digital codes does not automatically allow for obscured messages. The FCC rules require that messages must be intelligible and not encoded to obscure their meaning, except in specific cases like controlling space stations.

- **D: Never**  
  - **Explanation**: This choice is incorrect because there is a specific exception for control commands to space stations or radio control craft, as mentioned in the correct answer. Therefore, it is not accurate to say that it is never permissible.

### Summary of Rules:
- Messages must generally be clear and intelligible.
- Encoding to obscure meaning is only allowed for specific operational purposes, such as controlling space stations or radio control craft.

This understanding is crucial for compliance with FCC regulations and for passing the Extra Class exam.