DDP 2.0 (Disc Description Protocol)
DDP is an earlier format that was used by DVD replication facilities. Before CMF (Cutting Master Format) became a standard, a DVD-R disc could be used for testing a DVD-Video movie project, but could not be used as the master image. When DDP was the standard, you still had to write your project to DLT tape. DDP has been replaced by the Cutting Master Format, and you can supply either a DVD-R or a DLT tape as your master image.
CMF (Cutting Master Format)
CMF is the more common format for DLT tapes. DDP is an option in DVD Studio Pro because some replication facilities may require DDP format.