In what scenario must you assign a default value for a read-only control?

Assigning a default value to a read-only control is essential in scenarios where the control is defined as required. A required control signifies that the user must provide some input or confirmation before proceeding. In cases where the control is set to read-only, it cannot be altered by the user, which means that without a default value, the system might not have the necessary information to process or validate the required field. By assigning a default value, the control is effectively populated, ensuring that the user has an automated response that fulfills the requirement.

Situations where the control is defined as optional do not necessitate a default value since the absence of user input does not impact the requirement of the process. Similarly, if the control is hidden, there would be no need for a default value since the user is unaware of the control's existence. Lastly, in the case of replication, the read-only nature generally ensures that the values are consistently represented from the source, making a default redundant if the values are successfully populated during the replication process.