For anyone interested Ven. Anālayo has just published a new book,
“Early Buddhist Oral Tradition”
From the intro: “In the following pages I examine the early Buddhist oral tradition from the viewpoint of its formation and transmission. The central question I intend to explore is how best to understand its dynamics: What is the most appropriate model for interpreting the existence of numerous variations between versions of a discourse preserved by different reciter lineages, given that these same parallels also show a remarkable degree of similarity and correspondence (together with exhibiting features of memorization that point to a concern with accurate transmission)?”
The book starts with his analysis on the transmission of the pātimokkha.