Yes. This is something I thought about before. It is understandable why “suddhāṭṭhaka” does not appear in the Sutta Pitaka or the Vinaya Pitaka. I do not understand why it does not appear in the Abhidhamma Pitaka.
- But, of course, it is described in the Commentaries to the Abhidhamma.
- See, for example, Bhikkhu_Bodhi-Comprehensive_Manual_of_Abhidhamma,” by Bhikkhu Bodhi (2000). A pdf file can be downloaded (click the link to open the pdf).
Abhidhamma Pitaka was completed well after the Parinibbana of the Buddha. The Buddha described the critical concepts to Ven. Sariputta and it took several hundred years for the bhikkhus of the lineage of Ven. Sariputta to finalize the details. See “Abhidhamma – Introduction.”