जात्वपूर्वम्

Operational rule vidhi

The finite verb optionally retains its accent after जातु when this जातु is not preceded by another word.

Word by word (padaccheda)

Indeclinable जातु avyayaSubstitute / term अपूर्वम् prathamā · ekavacana

Indeclinable An avyaya such as च "and", वा "optionally", न "not".
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, dashed ones pratyāhāras (names for classes of sounds or affixes). Hover or tap one to see its card.

Full reading

जातु अपूर्वम्

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

Commentary

The finite verb optionally retains its accent after जातु when this जातु is not preceded by another word.
Thus जा꣡तु भोक्ष्य꣡से, जातु अध्यष्य꣡से, जातु करिष्या꣡मि । Here से is anudatta by 6.1.186, as it is an Sarvadhatuka affix coming after an अदुपदेश; the word जातु is first acute, as it is a Nipata. Why do we say 'when not preceded by any other word'? Observe:- कटं जातु क॒रि॒ष्य॒ति॒ ॥ The word कटं is end-acute as it is a फिट् or noun.

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