DLP 15.X
DLP 16.X
In case you heavily modified the system-defined data identifier and you start to see some issues and want to get the default back, you will need to get another DLP Enforce which still has the system-defined data identifier needed:
1 - Create a simple policy using the needed DI.
2 - Export the policy in xml format.
3 - Import the exported policy in the Enforce console where you need to restore the default DI.
After the import, the system-defined data identifier will be restored.