Most CDs from 1994 onward can be identified from the various numbers found on the mirrored data side. These are used to help identify the source of a CD. They are known as the “SID” (Source Identification Code).
Two identification codes have been implemented:
Mastering SID Code – This identifies the plant that manufactured the master.
Mould SID Code – This identifies the plant where the disc was pressed.
- The Mastering code always starts with a letter “L” for example “IFPI L123” and is found on the mirror part of the CD.
- The Mould code is found in the (often see trough) plastic inner ring of the CD and if often very hard to read. A magnifying glass can be helpful here.
The CD matrix is the longer code which usually contains a pressing number (which sometimes includes the catalog number) along with the barcode and the name/logo of the CD manufacturer.
You can read more about SID in the “SID CODE implementation guide” which can be found HERE and more details about the CD matrix HERE.