ciṇ is optionally the substitute of cli , when ta - 3rd Person Singular of ātmanepada follows after a root which ends with a vowel and when the object itself is spoken of as the agent.,
A reflective verb is one in which the object is spoken of as the agent. In reflective verbs therefore, चिण् is employed after roots ending in vowels; as अकारि कटः स्वयमेव 'the mat became made of itself. This is an optional rule (प्राप्तविभाषा). Therefore we have also अकृत कटः स्वयमेव; similarly अलावि or अलविष्ट केदारः स्वयमेव 'the embankment broke of itself.
But in verbs other than those that end in vowels, i.e. in those which end with a consonant, the चिण् is obligatory in the reflective voice, and not optional; as अभेदि काष्ठम् स्वयमेव 'the wood split of itself'. So also in verbs other than reflexives; as अकारि कटो देवदत्तेन.,