तस्य लोपः

Operational rule vidhi

The इत् letter is elided during the प्रक्रिया.

Word by word (padaccheda)

Target तस्य ṣaṣṭhī · ekavacanaSubstitute / term prathamā · ekavacana

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.

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Full reading

तस्य

As a rewrite rule (sketch from case endings)

तस्य →

Replace tasya with lopaḥ. Inherited words (anuvṛtti) may add further conditions.

Commentary

Of this, (namely of that which has been called इत् ), there is elision.
This sutra declares the function of इत्; namely it is a mere indicatory letter, and must be rejected. It is useful only as a mnemonic and is not a part of the term.

The word tasya in the sutra indicates that the substitution of lopa must be in the place of the whole term called इत्, and not only in the place of the final letter, which last is the general rule (see. 1.1.52). Therefore, the whole of ञि, टु and डु is rejected and not only their finals.

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