The final o of a vocative singular [[2.3.49]] before the word iti according to śākalya , in a secular or non-vedic literature is a pragṛhya,
This sūtra gives the opinion of the Rishi Sakalya, so that it is an optional rule. Thus both forms वायविति (formed according to the general rule of sandhi) and वायो इति (where ओ is pragrihya) are correct.
In ârsha literature the sandhi is imperative, not optional, as एता गा ब्रह्मबन्धवित्यब्रवीत्.
The mention of the name of any sage, such as that of Sakalya in this sūtra, serves generally one of the two purposes :- (1) either it makes the rule an optional one, vibhåshartham, or (2) the mention is merely for the sake of showing respect to the particular sage, the rule would have stood as well without such mention; pujártham, as the word Kåsyapa in sutra 1.2.15.,