saṅkhārupekkhā-ñāṇa: the 'equanimity-knowledge with regard to the formations of existence', is one of those kinds of knowledge which form the 'purification by knowledge and vision of the path-progress' (s. visuddhi, VI, 8). "It is known by 3 names: in the lowest stage it is called 'knowledge consisting in the desire for deliverance' (muccitu-kamyatā-ñāṇa); in the middle stage it is called the 'reflecting contemplation' (paṭisaṅkhānupassanāñāṇa); in the last stage, however, i.e. after attaining the summit, it is called the 'equanimity-knowledge with regard to the formations of existence' " (Vis.M. XXI).

Buddhist Dictionary, Manual of Buddhist Terms and Doctrines, by NYANATILOKA MAHATHERA