[173] What is the fine-material-sphere plane (rūpāvacarā bhūmi)? Making the Brahma world the limit below, and making the Akaniṭṭha devas the inclusion above — whatever mind (citta) and mental factors (cetasika), dhammas that move about within this interval, that are included herein, belonging to one who has entered upon an attainment (samāpanna), or to one who has been reborn there (upapanna), or to one who dwells in happiness in this very life (diṭṭhadhammasukhavihāra) — this is the fine-material-sphere plane.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.