There is optionally the vocalisation of the śyā followed by niṣṭhā affixes, when the upasargas abhi and ava precede it.,
Thus अभिशीनम् or अभिश्यानम् घृतं, अवशीनम् or अवश्यानम् वृश्चिकः ॥ This option applies even when the word means \coagulation\ and \cold\. As अवशीनं or अवश्यानं घृतं, मेदः ॥ अवशीतो or अवश्यानो वायुः, &c. अवशीतं or अवश्यानमुदकं ॥
The पूर्व in this sutra serves the same purpose as in 6.1.23. Thus अभिसंशीनं or अभिसंश्यानं, अवसंशीनं, अवसंश्यानं ॥ According to the author of Siddhanta Kaumudi, the word पूर्व shows that it is a vyavasthita vibhasha, hence there is no option allowed when अभि and अव are in the middle, as, समभिश्यानं, समवश्यानं ॥ Here we cannot have the alternative forms समभिशीनं &c.,