The affix u comes after the roots of the tanādigaṇaḥ (8th Conjugation) and after the verb kṛ 'to make', when a sārvadhātuka affix follows, signifying the agent.,
This debars शप्. As तन् + उ + ति = तनोति 'he expands'; कृ + उ + ति = करोति 'he makes'. Though the root कृ is included in the list of the Tanadiverbs, for which see Dhatupatha, yet its separate enunciation in the present sutra is for the sake of making a restrictive rule with regard to this verb; that is to say, the root कृ is a Tanadiroot only for the purposes of taking the affix उ; all the other operations of Tanadiverbs are not to be performed upon it. Thus the rule (II. 4.79.) does not apply to कृ. Thus अकृत and अकृत्याः; the सिच् elision being compulsory and not optional.,