The role of the presbyters of the Roman church is emphasised in the first of the canons cited here – they can be sent as papal legates to sit in ecclesiastical juries alongside the bishops of the place.
Philip and Asellus are such legates, but only bishop Faustinus speaks on the occasion.
The canons are cited again in the letters of the Council of Carthage to the successor of Zosimus, Pope Boniface I (, ed. Munier 1974: 158-159. Several other remarks about Philip and Asellus are made there, but they simply confirm their role as legates and do not give us any other information, so we have omitted them.
The letter of Zosimus to his legate has also been published as Letter 15 of Zosimus (Patrologia Latina 20, 681-682).