[615] Which form (rūpa) is internal and not the form element (rūpa-dhātu)?
The eye base (cakkhāyatana) … the body base (kāyāyatana) — this is the form that is internal and not the form element.
Which form is external and the form element?
The form base (rūpāyatana) — this is the form that is external and the form element.
Which form is external and not the form element?
The sound base (saddāyatana) … edible nutriment (kabaḷiṅkāro āhāro) — this is the form that is external and not the form element.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.