च्च्ः-वोः श्-ऊड्ः-अनुनासिके च

Thus प्रश्नः, विश्नः from प्रच्छ and विच्छ, with the affix नङ् 3.3.90 the च्छ being replaced by श ॥ Similarly from the root सिव् we have स्थोनः thus: सिव् + न (Unadi III. 9). = सि + ऊ + न = स्थू + न = स्थोनः 7.3.84. Here the ऊ is added to the stem prior to the scope being given to the guna rule of 7.3.86, otherwise the form would be सिव् + न = सेव् + न = से + ऊ + न ॥ Having thus added ऊ, before scope could be given to the guna rule 7.3.86, we make sandhi of सि + ऊ = स्थू, because semivowel substitution is antaranga operation and of wider scope than guna, and the maxim of वार्णादाङ्ग बलीयो भवति has no scope here. \An operation which is taught in the Angadhikara, and affects the anga or stem, possesses force than an operation which concerns a combination of letters (i. e. is taught in a sandhi rule)\.

With क्वि we have शब्दप्राश् formed with क्विप् (Unadi 11.57 ) added to प्रच्छ, there is no vocalisation of the semivowel र, and there is lengthening of अ, and च्छ changed to श. So also गोविश् ॥

Of the change of व into ऊ we have the following :- अक्षद्यूः, हिरण्यद्यूः (दिव् + क्विप् = दि + ऊ = द्यूः) ॥ Here the ऊ substitution is Bahiranga, and दि + ऊ = द्यू, the change of इ into य is antaranga, therefore on the maxim of असिद्धं बहिरङ्गमन्तरङ्गे (a bahiranga is non-existent for the purposes of an antaranga); there should be no change of इ into य, for ऊ is non-existent. That maxim is however set aside by नाजानन्तर्ये बहिष्ट्व प्रक्लृप्तिः \A bahiranga operation is not regarded as bahiranga, and consequently asiddha, when an antaranga operation is to take effect, which depends on the immediate sequence of a vowel and something else\.

So also before a jhaladi affix; as प्रच्छ + क्त = पृष्टः, पृष्टवान् (क्तवतु), पृष्ट्वा (क्त्वा); here च्छ is changed to श, there is vocalisation by 6.1.16, and श changed to ष by 8.2.36.

So also व is changed to ऊ as, द्यूतः, द्यूतवान्, द्यूत्वा ॥

When the affixes are not ङित् or कित्, the rule does not apply: as द्युभ्याम्, द्युभिः ॥ Some do not read the anuvritti of कित् and ङित् into this sutra, and explain द्युभ्याम् and द्युभिः by 6.1.131 : उ short being substituted for व of दिव् ॥

In \छशां ष\ 8.2.36 the letter छ should not be taken, because by the force of the present sutra, श is ordained to come every where in the place of छ ॥

The indicatory ठ् in ऊठ् is for the sake of distinguishing this ऊ in sutras like एत्ये धत्यूठ् सु 6.1.89. In the sutra वाह ऊंठ् 6.4.132 there is also indicatory ठ् ॥,