After verbs ending in ṇi and after ās 'to sit' and śranth 'to loose', there is the affix yuc when the word to be formed is feminine.,
This excludes the affix अ (III. I. 102). Thus कृ + णिच् = कारि; कारि + युच् = कारणा (the इ is elided by 6.4.51) 'the causing to do'; हारणा 'the causing to take'; आसना 'the sitting'; श्रन्थना 'the loosening'. How do we get the form आस्या ? It is the feminine of आस्य formed by adding ण्यत् to the root आस् by 3.1.124. Is not that rule made non-applicable by rule 3.1.94, which declares that वाऽसरूप rule does not apply to Feminine affixes? Yes, that is, however, not total exclusion. The phrase अस्त्रियाम् in (III 1. 94) is to be interpreted thus:- \Non-uniform affixes prohibit each other, when they belong to the class of affixes especially ordained for the feminine nouns; such as the affix क्तिन् 3.3.9, क्यप् 3.3.98, अ 3.3.102: That is to say, an utsarga-feminine affix will be always superseded by an apavada-feminine affix; but a feminine affix in general will not supersede another affix which is not enjoined in the feminine gender especially. In other words, feminine affixes inter se supersede each other totally, but not so with regard to general कृत् affixes\. Now by the present sutra the root आस् takes युच्; this totally excludes other feminine affixes like अ 3.1.102; but it does not exclude the non-feminine affix ण्यत् ।
The root श्रन्थि taken here belongs to the Kryadi class, meaning 'to loosen' and is not the श्रन्थ of Churadi class, for the latter would be included, as a matter of course, by belonging to the Churadi class which class of verbs take the affix णिच् ।
Vart:- The verbs घट्ट 'to move', वन्द 'to praise', and विद 'to feel', should also be enumerated, as taking युच्. Thus घट्टना 'shaking', वन्दना 'praising', वेदना 'knowledge, feeling, pain'. The verb घट्ट here belongs to the Tudadi class, and means 'to move' and not घट्ट of the Churadi class, for that is already included by being णिजन्त ।
Vart:- The affix युच् comes after इष् when it does not mean 'to desire'. Thus अध्येषणा 'solicitation'; अन्वेषणा 'the searching after'.
Vart:— So also optionally when इष् takes the upasarga परि; as, पर्येषणा or परीष्टिः 'investigation by reasoning'.,