To add an external identifier to an object, search for the appropriate classification scheme, then specify a value.
In the Details area for the object, click the External Identifiers tab.
The External Identifiers table, which can be empty, appears.
A Details Panel window opens.
Type a name and, optionally, a description for the external identifier.
Click the Select ClassificationScheme button.
A ClassificationScheme/Concept Selector window opens.
Expand the ClassificationSchemes node, then select a classification scheme that has no concepts.
Click OK to close the ClassificationScheme/Concept Selector window.
The classification scheme appears in the Details Panel window.
Type a value in the Value field.
Click Add to save the new object and close the Details Panel window.
Click Apply in the Details area for the object.