In this portion of the sūtras, in which there is reference to verbal roots, an affix which is calculated to debar a general one, not being of the same form, optionally debars it; but not so in the case of feminine affixes -- striyāṃ ktin [[3.3.94]].,
Thus the affixes ण्वुल् and तृच् (III. I. I33) are general affixes applicable to all roots in forming nouns of agency; and the sutra (III. I. I33) which ordains these affixes, is an utsarga or a general rule; while the sutra (III. I. I35) ordaining the affix क्र after verbs having a penultimate इक् vowel, and the roots ज्ञा, प्री and कृ is an apavada or a special aphorism. In the latter case, therefore, optionally we may have the affixes ण्वुल् and तृच् also. Thus क्षिप् is a root that has a penultimate इ belonging to the pratyahara इक्; and therefore, in forming the noun of agency from it, the affix क will have to be applied by rule 135 of this chapter already mentioned; thus विक्षिप् + क = विक्षिप् + अ =विक्षिपः; but this special rule however does not debar the operation of the general rule, and we have optionally विक्षिप् + ण्वुल् =विक्षेपकः; an विक्षिप् + तृ =विक्षेप्तृ nom. sing. विक्षेप्ता.
Why do we say 'not being of the same form'? Because if two affixes have the same form, the present rule will not apply; and in the case of such affixes, the special affix will debar the general affix. Thus the affixes अण् and क are, when stripped of their indicatory letters, affixes having the same form i.e. अ; and therefore the sutra (III. 2. I.) ordaining अण् as a general rule, will be always debarred by sutra 3.2.3 ordaining क, as the latter is a special sutra applicable only to those roots which end in long आ, or which are simple roots not compounded with any preposition. Thus गो + दा + क = गोदः 'giver of cows'. So also कम्बलदः 'blanket-giver'. In these cases we cannot have the affix अण्.
It follows from this sutra as a necessary corollary, that the addition of indicatory letters does not make two or more affixes dissimilar in form (असरूप) when their essential effective element is the same. Thus the affixes क, अण्, अच्, ण् &c. are similar.
Why do we say 'but not so in the case of feminine affixes'? Because in the case of feminine affixes, a special affix will debar a general affix, though they may be dissimilar in form. Thus sutra 3.3.94 ordaining क्तिन् in forming feminine nouns from roots is a general or utsarga rule, while sutra 3.3.102 ordaining अ after roots that have already taken some affix is a special or apavada rule, and though अ and ति are dissimilar in form, they being feminine affixes, the former will always debar the latter. Thus the compound desiderative roots चिकीर्ष and जिहीर्ष will form feminine nouns in आ and not by क्तिन्. Thus चिकीर्षा and जिहीर्षा and not चिकीर्षति &c.,