चक्षिङः ख्याञ्

ख्याञ् is the substitute of चक्षिङ् 'to perceive, to tell', when any आर्धधातुक affix is to be applied.
आख्याता 'he will perceive or tell'; अख्यातुम् 'in order to tell;' अख्यातव्यम् 'must be told.' The substitute being like the principal, चक्षिङ् being always Atmanepadi 1.3.12, ख्याञ् would have also been always Atmanepadi. But in that case the letter ञ् would have no scope; it therefore follows that ख्याञ् is not always Atmanepadi, but under conditions mentioned in 1.3.72.

Vart:- This substitute is also said to begin with क्श instead of ख्य. Thus अक्शाता, आक्शातुम्, आक्शातव्यं.

Vart:- Prohibition must be stated when meaning 'exclusion'; as दुर्जनाः संचक्ष्याः 'bad men should be excluded.'

Vart:- Prohibition must be stated when the affixes अस and अन follow : as नृचक्षा राक्षसः 'the Rakshasas are cruel.' This is Vedic Sanskrit; modern नृचक्षः. The meaning of the root चक्ष् here, is 'to injure.' So also निचक्षणः पण्डितः; here the affix is अन.

Vart:- Substitutes are made diversely in denoting appellatives and not qualities and in the Vedic Sanskrit; as अन्नम् 'food' (here the substitute जग्धि does not replace अद); वधकम् 'killer' (वध being substituted for हन् before ण्वुल्); गात्रं 'body' (गा is substituted for इण before the unadi affix ष्टन्); विचक्षणः (here चक्ष is not replaced by ख्या before अन); अजिरम् 'a court yard' (here अज is not replaced by व्यै as the next sutra 56 requires.)