The Blue Book is the informal name for the standard specification document for stamped multisession (also known as the enhanced CD or E-CD) disk format, developed in 1995 from a supplement to Philips and Sony's 1988 Orange Book. The Blue Book defines a format for enhanced CDs for inclusion of multimedia data (such as video clips, text, and images) on a standard audio CD. The disks play normally on a CD-player, and display the extra data when they are played on a device with multimedia capabilities, such as a computer's CD-ROM drive, or a CD-i player.
Like all CD formats, the Blue Book specifications are built on the details of the Red Book, which defined the format for audio CDs. The Blue Book specifies two sessions: up to 99 Red Book audio tracks in the first session (closest to the center of the disk), and a Yellow Book-based data track in the second session (closest to the outside edge of the disk). Other Blue Book details include the Red Book disk specification, file formats (including CD Plus information files), and an ISO 9660-compatible directory structure to organize the various types of data. The Blue Book is supported as a licensed standard definition by Philips, Sony, Microsoft, and Apple.