रैवतिकादिभ्यश्छः

Operational rule vidhi

The affix छ comes in the sense of 'this is his' after the words रैवतिक etc.

Word by word (padaccheda)

Left context रैवतिक- आदिभ्यः pañcamī · bahuvacanaSubstitute / term छः prathamā · ekavacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.

Dotted words are technical terms. Hover or tap one to see its card.

Full reading

रैवतिक-आदिभ्यः छः

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

Commentary

The affix छ comes in the sense of 'this is his' after the words रैवतिक etc.
All these words end with Gotra affixes, and require वुञ् 4.3.126, is ordains छ instead. Thus रैवतिकीयः, स्वापिशीयः &c.

1 रैवतिक, 2 स्वापिशि, 3 क्षैमवृद्धि, 4 गौरग्रीवि (गौरग्रीव), 5 औदमेघि (औदमेयि), 6 औदवापि (औदवाहि) 7 बैजवापि.

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.