Leading you to an educated decision.
1- Compact Disc. A 4 3/4", multilayer, polycarbonate-plastic, digital recording medium that can hold data or hi-fi stereo audio. Information is "burned into" a CD by a laser that pits the surface of the reflective recording layer. an optical device in a CD drive reads these "blemishes" as binary data.
2- The international term for main cross-connect. See MC.