Zaydun (nominative), Zaydan (accusative), and Zaydin (genitive) are case forms of one declinable proper name. The tanwīn does not create their case; the governing construction does.
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Three Case Forms
Tanwīn: Five Types, Their Function, and Omission
Zaydun (nominative), Zaydan (accusative), and Zaydin (genitive) are case forms of one declinable proper name. The tanwīn does not create their case; the governing construction does.