[174] What is the plane pertaining to the formless sphere (arūpāvacarā bhūmi)? Making the devas who have reached the sphere of infinity of space (ākāsānañcāyatana) the boundary below, and making the devas who have reached the sphere of neither perception nor non-perception (nevasaññānāsaññāyatana) the limit above, the dhammas—mind (citta) and mental factors (cetasika)—that are included therein, within this interval, whether of one who has attained [that attainment], or of one who has been reborn [there], or of one who dwells in pleasure in this very life—this is the plane pertaining to the formless sphere.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.