What is the ontological status of beings in the arūpa-lokas according to the early Nikāyas?

In the early Buddhist cosmological framework, the “formless realms” (arūpa-lokā) namely the spheres of infinite space, infinite consciousness, nothingness, and neither-perception-nor-non-perception are frequently described as planes of rebirth accessible through mastery of the corresponding immaterial attainments (arūpa-samāpatti). However, the precise ontological status of beings reborn in these realms remains ambiguous. ---------- **1. What constitutes the “individual” in the arūpa realms?** If rūpa is entirely absent, are such beings to be understood purely in terms of residual viññāṇa (consciousness), or as configurations of the remaining aggregates (vedanā, saññā, saṅkhāra, viññāṇa)? **2. How should we interpret the apparent continuity of identity in these realms?** Do the Nikāyas support a model of minimal subjectivity (e.g., “bare consciousness”), or do they resist any substantialist reading even at this level?