इतश्च लोपः परस्मैपदेषु

Operational rule vidhi

In the परस्मैपद affixes the इ is optionally elided in the लेट् (Vedic Subjunctive).

Word by word (padaccheda)

Target ṣaṣṭhī · ekavacanaIndeclinable च avyayaSubstitute / term prathamā · ekavacanaRight context saptamī · bahuvacana

Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
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.
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. Hover or tap one to see its card.

Full reading

च

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

As a rewrite rule (sketch from case endings)

→ /

Replace itaḥ with lopaḥ when parasmaipadeṣu follows. Inherited words (anuvṛtti) may add further conditions.

Commentary

In the परस्मैपद affixes the इ is optionally elided in the लेट् (Vedic Subjunctive).
The वा of the last sutra is understood here also. Thus जोषिषत् (Rig. II.35. I). तारिषत् (Rig. I.25.12. मन्दिषत् । In the alternative, it is not elided as पताति विद्युत् (Rig. VII.25.1). उदधिं च्यावयाति । The इ of इट्, वहि and महि of the Atmanepada are not elided.

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