A variety of strategies exist to mark the object[1] (also known as P, patient, or DO, direct object) in a transitive sentence. Besides the explicit use of the noun or pronoun with or without case marking, strategies include verbal agreement, the use of non-verbal morphemes, and fixed word order. Strategies may be obligatory or optional. When evaluating sentences for this parameter, first- and second-person objects also should be considered.

Types:

PNPonly: The object is exclusively marked through the use of a noun or independent pronoun, and with the exception of required word order in some languages, no other morphosyntactic strategies for object marking are available.[2]

PNPobl: The object is obligatorily marked by the explicit use of the noun or an independent pronoun, but other strategies also exist.[3]

PNPnonobl: The object may be optionally marked through the explicit use of the noun or an independent pronoun.[4]

PNPor: The object is marked through the explicit use of the noun or an independent pronoun; only in the absence of these are other strategies available.[5]

+Agr: The object is marked through the use of morphosyntactic agreement on the verb.[6]

+Clit: The object is marked through the use of a clitic.[7]

+Aux: The object is marked through the use of an auxiliary, which simultaneously marks other grammatical categories, such as tense, aspect, and mood.

+Clsfr: The noun is marked through the use of a classifier, which simultaneously refers to the object.

+WO: The object is marked through the use of a specific word order. [8]

When a language displays more than one strategy, multiple values can be listed. If one strategy is dominant, a slash (/) can separate the two values, with the dominant value appearing first and the grammatically restricted strategy appearing second; if neither is dominant, they are listed with an ampersand (&) separating the two. A plus sign (+) may be used instead of an ampersand to indicate that the strategies must apply simultaneously. Parentheses indicate that use of the strategy is not obligatory.

[1] The object (P) is the entity that undergoes the action of the transitive verb or is the result of it. In nominative languages, this is called the direct object.

[2] Both of these conditions must apply. If this value applies, the value of Person marking on verbs must be NoPM.

[3] This value should appear alongside another value, separated by a plus sign.

[4] This value should appear alongside another value, separated by a plus sign. For example, NPPNonobl+Agr refers to a language in which the object (and potentially some of its properties) may be marked by verb inflection, and the verb can mark the object without the use of an explicit noun or pronoun.

[5] This value should appear alongside another value, separated by a plus sign.

[6] This value includes affixes, internal flexion, and the use of bound person markers that attach to the verb (with or without agreement). It also covers objective conjugation, in which the verb is marked for the existence of the object, or for some grammatical category of the object, such as person, number, definiteness, or class. If this value applies, the value of Person marking on verbs cannot be NoPM or APM.

[7] Clitics attach not (or not only) directly to the verb but to a structure encompassing it, such as a phrase or clause.

[8] The object is required to appear in a given position, such as directly preceding or following the verb.