What to write in the BitLocker identification field?

Question

Active Directory

1) Hello, I've browsed through a bunch of the Internet and still don't understand what needs to be registered, and most importantly why:

The only thing I understand is that if the setting Deny writing to devices configured in another organization is enabled is set to Enabled, then for the flash drive it is manually required through the command manage-BDE.exe -si D: enter the value from the "BitLocker Identification Field" field.
2) Why the second field "Allowed BitLocker Identification Field"?