Lal said: 6. The final sutta says when one understands the above, one comprehends “Rūpa dhātu, arūpa dhātu, nirodha dhātu.”
In this context, the arūpa dhātu means the namaloka?
The reason why I asked is that there are rūpa(hadaya vatthu) in arūpa realm. So arūpa dhātu is not same the arūpa loka.