CD Duplication Terminology Here we will take a brief look at the most common terminology that is used in CD duplication. BLERBlock Error Rate. This is the raw digital error rate before any type of error correction.CDThis the Compact Disc, a digital medium that's formed of a 12cm polycarbonate substrate, a reflective metalized layer, and a protective lacquer coating.CD-RCompact Disc-Recordable. The term CD-R is used to...... Similar Editorial : Duplication vs by Tina Rideout. | Source : Computer Networking