This allows the DCC SEND connection to survive where an FTP connection might fail. The size of the packets is up to the client, and may be set by the user. Smaller packets result in a higher probability of survival over bad links. The sender should not continue to transmit until the recipient has acknowledged all data already transmitted. Additionally, the sender should not close the connection until the last byte has been acknowledged by the recipient.
Users generally verify the transfer by checking file sizes.
Note also that no provision is made for text translation. This should probably be reviewed and reduced.