One type of mutual etiquette amongst the Sāṃbhojika (commonsel co-religionist) ascetics, in which the exchange of clothes, pots, utensils etc. is permitted.
upadhirvastrapātrādistaṃ sambhogikaḥ sambhogikena sārddhamudgamotpādanaiṣaṇādoṣairviśuddhaṃ gṛhṇan śuddhaḥ...
(Sama 12.2 Vṛ Pa 21)