In this portion of the sūtras in which there is a reference to verbal roots, any affix except tiṅ - tense affixes, is called kṛt ,
Thus the affixes तव्यम् &c. are कृत्. All affixes up to the end of this Book belong to this class. These are affixes by which substantives are formed from verbal roots; and they have, therefore, most aptly been termed primary affixes. Words formed by these affixes will be Pratipadikas or crude forms or nominal bases 1.2.46. Thus कृ + तव्यं = कर्तव्यं. Why do we say 'except तिङ् affixes'? Observe चीयात् 'may he collect', स्तुयात् 'may he praise' which form verbs and not nouns.,