The present study aims at investigating the nature of object indexed elements in Persian. This is an essential element for deciding about the layered structure of the clause in the framework of the Role and Reference Grammar.Because of the inefficiency of the mere formal approaches, we appeal to the Role and Reference Grammar, a functional-structural model which considers all morpho-syntactic units with regard to their usage in the context. The goal of the Role and Reference Grammar is to uncover the universal aspects of the clause structure, without imposing features on languages in which there is no evidence for them. The research is descriptive-analytic and uses the standard colloquial Persian as its data. To do this, the data of standard spoken Persian are extracted from various resources and then analyzed syntactically.The behavior of indexed elements signifies that they have not turned into the agreement markers, although they behave like them somehow. So in representing the clause structure of transitive sentences, we posit the indexed elements in INDEX node outside the AGREEMENT node. In the absence of overt object noun phrase, the indexed element can function as the argument in the clause.
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