Usage is a special field based on PicklistSingle. It is the recommended field type to be used use when you want to define a term’s usage.
If a field is of type Usage, each possible picklist value is assigned to a global usage status:
Preferred: The term will appear as positive and recommended in Manage Grid and in TermTiger Search.
...
Admitted: The term will appear as allowed in Manage Grid and in TermTiger Search.
...
Deprecated: The term will appear as negative and forbidden in Manage Grid and in TermTiger Search.
...
Undefined: The term will appear as neutral without any usage information in Manage Grid and in TermTiger Search.
...