लङः शाकटायनस्यैव

In the opinion of शाकटायन only जुस् is the substitute of झि , in the लङ् (Imperfect Tense) of the roots which end in a long आ।
Thus अयुः, अवुः । In the alternative, we have अयान् and अवान् ।

Why is लङ् repeated here, when the context would have supplied this word; for the sutra applies to ङित् tenses, of which लुङ् being dealt with in the last, would have लङ् only to be dealt with by this aphorism, for no other ङित् tense (like लिङ् or लृङ्) can end in आ ? The repetition shows that the rule applies to those affixes which come after लङ् as लङ्, and not to those which come after another tense which is treated like लङ् । Thus लोट् is treated like लङ्, but for the purposes of this rule, लोट् would not be so treated. Thus the झि of लोट् will not be changed into जुस् by 3.4.109. Thus बिभ्यतु, जाग्रतु, विदन्तु । The word एव has been used in the sutra, for the sake of the subsequent sutra.