"Dual is a grammatical number category that refers to two entities. In the case of agreement, dual is also marked on the verb. Agreement may be consistent for various kinds of nouns (e.g. animate and inanimate nouns) and pronouns... The value is ‘1’ if there is verbal agreement with dual subject in at least one of the possibilities mentioned above. The answer is ‘0’ if dual is marked only on the verb or only on the noun."