Differential object marking is a pattern in which different subtypes of P-arguments are marked differently.
Strictly speaking, differential object marking (DOM) should be called "differential P marking", because "object" must be taken to mean "direct object" (= P-argument). There are two subtypes of DOM: differential object flagging (DOF) and differential object indexing (DOI) (Haspelmath 2026). ❡
The term DOM became well-known through Bossong (1985; 1991), though it was first used in Bossong (1982), building on Moravcsik (1978).
differential object marking (STR) = a strategy that is marginal for the passive–inverse voice construction in which there is a distinct, overt flag of higher animacy / higher information status – that is, higher-salience – Ps. Example: in Spanish, El director busca a un empleado ‘The director is looking for a [specific] clerk,’ the phrase un empleado ‘a clerk,’ referring to the P participant, uses the overt flag a. Differential object marking is not usually considered a strategy of the passive–inverse construction because the A participant is not reduced in salience, although the P participant is higher in salience. (Section 8.3)