Grammatical Sūtra: उपसर्गेऽदः upasarge'daḥ 
Individual Word Components: upasarge adaḥ
Sūtra with anuvṛtti words: upasarge adaḥ pratyayaḥ (3.1.1), paraḥ (3.1.2), ca (3.1.2), ādyudāttaḥ (3.1.3), ca (3.1.3), dhātoḥ (3.1.91), kṛt (3.1.93), kriyāyām (3.3.10), kriyārthāyām (3.3.10), bhāve (3.3.18), akartari (3.3.19), ca (3.3.19), kārake (3.3.19), saṃjñāyām (3.3.19), ap (3.3.57)
Type of Rule: vidhi
Preceding adhikāra rule:3.2.134 (1ā kveḥ tacchīlataddharmatatsādhukāriṣu)
Description:
The affix 'ap' comes after the verb 'ad' (to eat) when an upasarga is in composition. Source: Aṣṭādhyāyī 2.0
[The kŕt 1.93 affix 1.1 aP 57 is introduced after 1.2 the verbal stem 1.91] ad- `eat, consume' (II 1), co-occurring with a preverb [to form an action noun 18 to denote a kāraka other than the agent 19]. Source: From Aṣṭādhyāyī of Pāṇini In Roman Transliteration translated by Sumitra M. Katre, Copyright © 1987. Courtesy of the University of Texas Press.