Warning displayed when keying in document attributes that are backed by a list and configured to use the Allow other values option.
When you start entering data to a document attribute backed by a List and meeting the criteria that Allow other values is active, it may be seen that a warning is shown before user is allowed to continue entering data.
The warning reads: "The typed value is not a known value. Please confirm you want to use it anyway. The rest of the cascading drop-down will continue to work.".