Ident

A request for a pilot to activate the aircraft transponder identification feature. This will help the controller to confirm an aircraft identity or to identify an aircraft. (PCG definition)
Air Traffic Control request for a pilot to push the button on the transponder to identify return on the controller’s scope. (PHAK definition)

Source: Pilot Contoller Glossary (PCG), Pilot Handbook of Aeronatical Knowledge

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