वा छन्दसि

Operational rule vidhi

The पूर्वसवर्णदीर्घनिषेध given by the sutra 'दीर्घाज्जसि च' is optional while deriving the Vedic forms.

Word by word (padaccheda)

Indeclinable वा avyayaRight context छन्दसि saptamī · ekavacana

Indeclinable An avyaya such as च "and", वा "optionally", न "not".
Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").

Dotted words are technical terms, dashed ones pratyāhāras (names for classes of sounds or affixes). Hover or tap one to see its card.

Full reading

वा छन्दसि

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

Commentary

In the Vedas, the long vowel may optionally be the single substitute of both vowels in these cases last mentioned.
Thus मारुतीः or मारुत्यः, पिण्डीः or पिण्ड्यः, वाराही or वाराह्यौ; उपानही or उपानह्यौ ॥

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