Cd´s and Dvd´s have the nasty habit to become unreadable due to data loss or aging at the very moment when one needs them most. Dvdisaster creates error correction codes to compensate read errors which are not correctable in the CD/DVD drive.
It tries to read as much data as possible from defective media. Afterwards unreadable sectors are recovered using the previously created error correction code. The maximum error correction capacity is user-selectable.
If you create the error correction code file in time and keep it at a safe place, you have a good chance of recovering the medium contents from typical read errors and to transfer your complete data onto a new medium.
This looks a lot like the par format to me. The par format is mainly used in the Usenet, its able to recover bad rar files and thus make a file that consists of many rar´s readable and unpackable again.
Useful tool, only thing you need to do is create a recovery code before some parts of the Cd or Dvd become unreadable.

CD Data Recovery Tools Overview
DVD Data Recovery Software
Data Recovery Tools: Encopy
CD DVD Data Recovery Software
Giveaway of the Day – Data Recovery Wizard
CD Recovery Toolbox
Check Media for Errors
Copy Data from partially unreadable files