Abhidhamma Kathātvatthu is the sophisticated high-level Dhamma explaining compatibility of things: Khandha, Āyatana, and Dhātu.
Other notes:
(Second front folio) “Seventh fascicle, forty-three folios in total”.
(Back cover) “Front cover of Gathāvatthu, seventh fascicle”.
(Left side of the first folio) “Gathāvatthu, seventh fascicle”.