俱舍論疏 5.99

5.99

論「此令大種至故名為定」，述有部兩釋也。定即等至異名，散無此能，故等至名唯目於定。二定無心亦有此能，故此二定亦名等至。

Regarding the treatise's statement, "Because this causes the primary elements ... it is therefore named an attainment": This sets forth two explanations of the Sarvāstivāda school. Samāpatti ('attainment') is an alternative name for dhyāna; a distracted mind lacks this capability, so the designation 'equipoise' (samāpatti) refers exclusively to meditational stabilization. The two mindless attainments also possess this capability, which is why these two attainments are also named samāpattis.