This paper proposes a nanosyntactic analysis of non-specific, specific unknown and specific known indefinite markers, as identified in Haspelmath (1997). The crosslinguistic analysis of syncretism between these three types of indefinite markers reveals that they form a particular hierarchy of structural containment, nonspecific < specific unknown < specific known. Using the methodological tools of the nanosyntactic framework (Caha 2009; Starke 2009, 2011), it is possible to propose a syntactic model explaining the derivation of non-specific, specific unknown and specific known indefinite markers and the attested patterns of syncretism observed cross-linguistically in paradigms of the three types of markers. In consequence, the analysis shows that the analyzed indefinite markers constitute a syntactic domain which conforms to the *ABA generalization (Bobaljik 2012).