The affix ini comes in the sense of 'enounced by him' the thing enounced being bhikṣu-sūtra and naṭa-sūtra after the words 1. karmanda 2. kṛśāśva,
Thus कर्मन्दिनो भिक्षवः, 'the mendicants who study the Bhikshu-sutra of Karmandin'. कृशाश्विनो नटाः 'the actors who study the Nata Sutra of Krisasvin.' Otherwise कार्मन्दकम् and काशीश्वम् ॥ See 4.2.66.,