MDS file: It is an optional media descriptor file that can be generated when creating a disc image from a CD or DVD. The format is a binary file with the magic number "MEDIA DESCRIPTORS" appearing in the beginning of the file. The MDS file contains metadata about the original media, specifically the position of the layer breaks or layer breach bit, a property of the copy protection feature of DVDs. An MDS file is then used in conjunction with its related disc image to re-create the DVD. It is called an MDS file because of its implemented file extension .mds. It could also be described as being an archive file of MDS format.