The affix ṅīp is optionally used after a prātipadika (Nominal Stem) expressive of colour ending with a gravely accented vowel and having the letter t as its penultimate letter and the letter n is substituted in the room of t,
Thus of एत 'variegated'; the feminine is एता or एनी 'variegated', so श्येता or श्येनी 'black', हरिता or हरिणी 'green'. All these words have udatta accent on the first vowel either by Rule 6.1.197 (ञ्नित्यादिर्नित्यम् \word formed by affixes having an indicatory ञ् or न् have udatta accent on the first vowel\:) because these words are formed by the Unadi affixes तन् (Un III. 86) and इतन् (III. 93), or by the Phit sutra 11. 10 (वर्णानां तणतिनितान्तानाम् \of words expressive of colour and ending in तण, or ति or नि or त, the udatta accent falls on the first vowel\).
Why do we say \expressive of color\? Observe प्रहृता, प्ररुता ॥ These words are also acutely accented on the first syllable, by rule 6.2.49 (गतिरनन्तरः \the first word retains its natural accent in a compound of a gati word with a word formed by the affix kta\). But as these words do not express color, their feminine does not take nip.
Why do we say \ending in a gravely accented vowel?\ Observe श्वेता 'white'. Here though the word expresses 'color', yet it has acute (instead of grave) accent on the final (by rule of Phit sutra I. 21 घृतादीनां च \the words ghrita &c. have udatta on the final\).
Why do we say \having the letter त as its penultimate letter\? Otherwise the affix nish will be employed in forming the feminine.
The words for the application of this rule must end in the letter अ in the masculine. Otherwise this rule will not apply. As शितिर्ब्राह्मणी 'a black Brahmani woman'. Here शिति is a word expressive of color, it has a penultimate त, has anudatta accent on the final 6.1.197 as it is formed by the affix क्तिन्; but as it does not end with अ, its feminine is not formed with nip.
Vart:- The affix hip comes also after the word पिशङ्ग; as, पिशङ्गी 'of tawny color'.
Vart:- There is prohibition in the case of the words असित and पलित; as असिता 'black' and पलिता 'grey'.
Vart:- According to some, the substitute क्नम् replaces the final of these two words असित and पलिता in the Vedic literature. As आसिक्नी (Rig Veda IX. 73. 29); पलिक्नी (R. Veda V. 2. 4). According to some authorities, these latter forms are valid in literature other than the Vedic:- As गतो गणस्तूर्णमसिक्निकानाम् ॥,