6.3.97
द्व्यन्तरुपसर्गेभ्योऽप ईत्
Operational rule vidhi
After 1. द्वि 2. अन्तर and prepositions, long ई is the substitute of अप्.
Word by word (padaccheda)
Left context द्वि- अन्तर्- pañcamī · bahuvacanaTarget अपः ṣaṣṭhī · ekavacanaSubstitute / term ईत् 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.
- Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
- 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
द्वि-
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
अपः → ईत् / द्वि-
Replace apaḥ with īt when it comes after dvi-antar-upasargebhyaḥ. Inherited words (anuvṛtti) may add further conditions.
Commentary
After 1. द्वि 2. अन्तर and prepositions, long ई is the substitute of अप्।
By 1.1.54, ई replaces the first-letter of अप् viz अ only. Thus द्वीपः, अन्तरीपः, नीपम्, वीपम्, समीपम् ॥ The samasanta अ is added by 5.4.74.
Vart:- Prohibition should be stated with regard to समाप ॥ समापं नाम देवयजनम् ॥ Others say after a Preposition in अ, the long ई substitution does not take place. Thus प्रापम्, परापम् ॥ The word upasarga strictly speaking denotes adverbs, and cannot be applied to nouns like अप्; here however, this word is used in a loose sense in the sutra. It means प्र &c.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.