The word mukha has acute accent (udātta) on the final after the preposition ap,
Thus अपमुख꣡म्, अपमुखः꣡ ॥ The compound is in one case Avyayibhava also, when rule 6.2.33 will be superseded. The separation of this from the last sutra, is for the sake of the subsequent aphorism, in which the anuvritti of अप only goes.,