आर्धधातुकं शेषः

The remainder i.e. the affixes other than तिङ् (Personal Endings) and those with an indicatory श् sub-joined to a verbal root are called आर्द्धधातुक।
Thus the affixes तृ, तुम्, तव्यम् &c. are आर्धधातुक affixes as in the following words- लविता, लवितुम्, लवितव्यम् । Here the augment इट् is added, because of these affixes being called ardhadhatuka by 7.2.35.

The word धातोः whose anuvritti began with sutra 3.1.91, is understood here also. So that the affixes in relation to the verbal roots get the name of sarvadhatuka and ardhadhatuka; the affixes applied to nouns do not get these names. Thus the case-affix भ्याम् when added to the noun लू, is not called an arthadhatuka affix, and therefore we have लूभ्याम्, लूभिः &c. Had these affixes been ardhadhatuka, they would have caused the guna of the base 7.3.84. Similarly the affixes त्वं and ता in the words वृक्षत्वं and वृक्षता are not ardhadhatuka affixes. Had they been so, there would have been the insertion of the augment इट् 7.2.35.

Similarly in sutra 3.1.5, the affix सन् is used without changing the sense, after the roots गुप्, तिज् and कित् । But as this affix is added without the enunciation of the word धातोः as it is in sutra 3.1.7, this सन् is not called ardhadhatuka, and does not take the augment इट्, as जुगुप्सते ।