You can choose to store the mappings in the Model repository.
You can enable the Persist Mapping option from the Hive Properties in the
Administrator | Preferences
view. Default is disabled. A TDM user can override this setting at the plan level. You can choose to persist mappings in the Model repository so that the mappings are available for future use. You can persist mapping if you want to troubleshoot a problem. After you persist mapping, you can view and edit the mappings.