According to the opinion of Northern Grammarians i is not substituted for that a which is obtained by shortening the long ā of the feminine (under sūtra ke'ṇaḥ [[7.4.13]]) when to the feminine in long ā there is no equivalent masculine, even when the negative particle precedes.,
As खट्वका or खट्विका, अखट्विका or अखट्वका, परमखट्वका or परमखट्विका ॥ When before the affix कप्, the stem is shortened in a Bahuvrihi, this rule will apply 7.4.15. There also, the अ must be substituted for the आ of a feminine word which has no corresponding masculine. But this rule does not apply when the negative compound is the synthesis of अविद्यमाना खट्वा अस्याः = अखट्वा, अल्पा अखट्वा =अखट्विका ॥ Similarly अतिक्रान्ता खट्वाम् = अतिखट्वा, अल्पा अतिखट्वा =अतिखट्विका ॥
Note: The word खट्वा is always feminine and has no corresponding masculine.,