a strategy for encoding the relation in major propositional acts ( modifier– referent, predicate– argument), in which there is a third morpheme that refers to the referent. The third morpheme is called an index. Example: Spanish las chicas cantaban 'the girls were singing' uses indexation to express the relation between the singing and the singers (the girls), with the 3rd person plural suffix -an. Indexation usually expresses the categories of person, number, and/or gender–class. Since personal pronouns usually express only those categories, personal pronouns are arguably also indexes. Often the referent/argument is left unexpressed when the indexical strategy is employed – hence, the referent/argument is expressed only by the index. Indexical strategies include person indexation, nonperson indexation, and classifiers. (Sections 3.3.2, 4.4, 6.2.2)