Intensive Outpatient Treatment (also known as IOP for Intensive Outpatient Program) is a primary treatment program recommended in some circumstances by a clinical and medical assessment. IOP may be recommended for those who do not need medically-supervised detox.
The genitive is the case (or function) of an inflected form of a noun or pronoun showing ownership, measurement, association, or source. Adjective: genitival. The suffix -'s on nouns is a marker of genitive case in English. Genitive case can also be indicated by an of phrase after a noun.
In Latin it is used to indicate any number of relationships that are most frequently and easily translated into English by the preposition of: love of god, the driver of the bus, the state of the union, the son of god. The genitive case in Latin is also used adverbially with certain verbs.