The BitLocker Recovery Key ID is used to find the specific Recovery Key for an encrypted client machine. With the Recovery Key, the user can unlock encrypted drives and perform recoveries. See the BitLocker Recovery Guide.
The Recovery Key ID to identify the client is like this:
The Recovery Key is like this:
To Run the BitLocker Recovery Process
Note - The Advanced button on the BitLocker Recovery Media screen offers other processes:
See Microsoft for the BitLocker Recovery Guide.