The participial affix may optionally get iṭ augment after 1. ruṣ 2. am 3. tvara 4. saṃghuṣ and 5. āsvan,
As रुष्टः or रुषितः ॥ By 7.2.48, the affixes after रुष् are optionally सेट्, and therefore by 7.2.15, the Nishtha after this verb would have been always anit; hence this optional rule. अभ्यान्तः or अभ्यमितः; तूर्णः or त्वरितः ॥ The त्वर् is exhibited in the Dhatupatha as ञित्वरा 1.8.2 i.e. with an indicatory long आ, and hence by 7.2.16. would have been anit always, this rule makes it optionally anit. So also, संघुष्टौ पादौ, or संघुषितौ पादौ, संघुष्टं or संघुषितं वाक्यमाह, संघुष्टौ or संघुषितौ दम्यौ ॥ घुष preceded by सम् will be optionally anit, even when having any sense other than that of 'proclaimed', as this subsequent sutra supersedes 7.2.23 so far. So also आस्वान्तः or आस्वनितौ देवदत्तः, आस्वान्तम् or आस्वनितं मनः ॥ स्वन् when preceded by आ, though denoting 'mind,' is optionally anit, in spite of 7.2.18, that rule being superseded so far by this subsequent rule.,