Constructions -IB BIT-, -IB BITIR-

The constructions "verb-IB BIT-" and "verb-IB BITIR-", i.e. the past gerund followed by the auxiliary verbs bit- or bitir- root meaning: 'to end', 'to finish'), expresses the completion of an action at its terminal point, but without any commitment on the relevance of the accomplishment for the time following the end of the action (no perfect value).
bit- is used for intransitive actions, bitir- for transitive (causative) actions.

- Intransitive, with bit-:

Yonib bitgan.
Having finished burning.

Chirib bitdi.
It has finished rotting.

- Transitive, with bitir-:

Xatni yozib bitirdi.
He has finished writing the letter.