deriv SD cv (1086) ashtadhyayi.com hei.de L 1086 ETT STT a 7.1.2 ALPH OLDHOMEPAGE NEWHOMEPAGE

Ayan;ey;In;Iy;iyaH pha;Dha;kha;ccha;ghAm pratyayAdInAm

आयनेयीनीयियः फॱढॱखॱच्छॱघां प्रत्ययादीनाम् ONPANINI 71002

At the start of an affix, replace —
ph फ् → Ayan आयन्
Dh ढ् → ey एय्
kh ख् → In ईन्
ch छ् → Iy ईय्
gh घ् → iy इय्.

So the affix Dhak has the letters eya एय, and the /kit causes /vRddhi —

vinatA- विनताॱ + /Dhak
→ vinatA- विनताॱ + eyak एयक् by this rule
→ vinat- विनत् + eyak एयक् by yasyetica
→ vainat- वैनत् + eya एय by kitica
→ !**vainateya- वैनतेयॱ "son of vinatA विनता"

And /phak is Ayana आयन as in

gArgya- गार्ग्यॱ + /phak → **gArgyAyaNa- गार्ग्यायणॱ

See also ThasyekaH.