(iḍāfa) Al- is not prefixed to non-final nouns in a genitival construction (Iḍāfa). For example, in shawāri‘ al-madīna (the city’s streets), the word is a non-final noun in the genitival construction. Hence, it cannot be prefixed with al- (it is already definite by virtue of the construction). Exceptions to this include genitival constructions where the first noun is a participle and the second noun is its object. This can be done if one of the following conditions is met. the first noun is dual; e.g. the first noun is sound masculine plural; e.g. the second noun also has al-; e.g. the second noun is the first noun of another genitival construction, and the second noun in this other construction has al-; e.g. the second noun is suffixed to a pronoun which refers to a noun that has al-; e.g. Al- has also been seen in poetic verses prefixed to non-final nouns in a genitival construction. An example is in the following couplet: Furthermore, the grammatical school of Kufa allows al- on the first noun in a genitival construction if it is a number. For example, the phrase “thalāthat aqlām” (three pens) may be read “al-thalāthat aqlām”. Vocation According to the Basra school of classical grammar, al- does not typically follow the particles of vocation. For example, one will not say “yā ar-rajul” (O the man). The proponents of the Basra camp give two exceptions. the word “Allah”; one may say “yā Allah” (O God) with or without pronouncing the hamza in “Allah”. direct quotation; one may say, for example, “yā al-Ḥasan” (O al-Hasan) to someone named al-Hasan. However, the Kufa camp of classical grammar, as well as many modern grammarians, allow al- to be prefixed to the object of vocation almost unconditionally. An example is given in the following couplet of poetry: Under this scheme, if the object of vocation is a single word and it is feminine, the particle of vocation will be followed by the particle ayyatuhā. And if it is masculine, it will be followed by the particle ayyuhā. Nunation (tanwīn) According to the classical grammarians Farrā and Kasā’ī, the overarching purpose of nunation is to differentiate between nouns and verbs. Thus a noun is given nunation so that it won’t be confused with a verb; for example the name would have been confused with a quadriliteral verb had it not been for nunation. Additionally, we know