The affixes ka -- prāgivātkaḥ [[5.3.70]], and akac (ak) -- avyayasarvanāmnāmakac prāk ṭeḥ [[5.3.71]], come after a word, noun or verb, when something or somebody not known is spoken of.,
This अज्ञात or want of knowledge refers not to the object itself, but to its relation with some other object. As अश्वकः 'whose horse?' गर्दभकः 'the ass' (of whom is this)? उष्ट्रकः &c. Similarly in उच्चकैः 'high' (is it so?) नीचकैः 'Is it low'? सर्वके 'was this agreed to by all'? So also विश्वके ॥ Similarly पचतकि \He cooks, is it?\ जल्पतकि 'He speaks, does he?',