DVDisaster Error Correction File
From Just Solve the File Format Problem
A DVDisaster Error Correction File is created by the dvdisaster software making use of Reed-Solomon error correction codes based on the contents of a DVD (or CD or BluRay disc), either an existing one or one you are in the process of creating. If it's a new disc being created, the program can store the error correction file on the disc itself; otherwise, it is created as a separate file. The correctness of the disc image can be verified by generating the same data from the disc and comparing it to the previously-generated file. If parts of the disc have gone bad and caused data loss, it may be possible to recover the lost data from the error-correction file.