BLUE BOOK

In 1995, Philips announced a specification to define "stamped multi-session" discs. A subset of that specification, designed expressly for stamped multi-session discs limited to two sessions (one music, one data), is known as Blue Book Standard or CD Plus.

This standard places audio data in the first track of the first session of the disc, where it can be recognized and played by CD-Audio players, and CD-ROM data in the second session of the disc, where it can only be accessible by CD-ROM drives controlled by personal computers.

The multiple sessions and tracks on the CD-Recordable disc can be recorded as entirely separate volumes, or so that each separate session contains "pointers" to link the information in earlier sessions to later sessions. Depending on the recording method, the resulting disc could appear as a logical whole, or as discrete sessions. These discrete, or linked, sessions could be Yellow Book or Red Book, in any order.

The advantage to CD Plus is that it is a single, defined, licensed standard supported by Philips, Sony, Microsoft, and Apple. It plays on CD-Audio players with no possibility of producing static and on many newer computers with CD-ROM drives.

The disadvantages are that there are many existing CD-ROM drives-approximately 40% of the installed base-that are not capable of playing multi-session discs. Even existing multi-session drives may require a driver upgrade in order to use these discs.