उपमानादाचारे

Operational rule vidhi

The affix क्यच् is optionally employed, in the sense of treatment after a word ending in a case-affix denoting the object of comparison.

Word by word (padaccheda)

Left context उपमानात् pañcamī · ekavacanaRight context आचारे saptamī · ekavacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
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

उपमानात् आचारे

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

Commentary

The affix क्यच् is optionally employed, in the sense of treatment after a word ending in a case-affix denoting the object of comparison.
Thus, पुत्रमिवाचरति छात्रं = पुत्रीयति छात्रम् 'he treats the pupil as a son'

Vart: So also in a locative case. As प्रासादीयति कुड्ये 'he dwells in hut as if it were a palace'. पर्यङ्कीयति मञ्चके 'in a cot he lies down as if he were on a royal bedstead; he treats a cot as a royal bedstead'.

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