CD-Text

CD-Text is an extension of the Red Book Compact Disc specifications standard for audio CDs. It allows for storage of additional information (e.g. album name, song name, and artist name) on a standards-compliant audio CD.
The specification for CD-Text was included in the Multi-Media Commands Set 3 R01 (MMC-3) standard, released in September 1996 and backed by Sony. It was also added to new revisions of the Red Book. The actual text is stored in a format compatible with Interactive Text Transmission System (ITTS), defined in the IEC 61866 standard. The ITTS standard is also applied in the MiniDisc format, as well as in Digital Audio Broadcasting technology and Digital Compact Cassette.
Storage.
The CD-Text information is stored in the subchannels "R" to "W" on the disc. This information is usually stored in the subchannels in the lead-in area of the disc, where there is roughly five kilobytes of space available. It can also be stored on the main program area of the disc (where the audio tracks are), which can store about 31 megabytes. Since the R to W channels are not used in the Red Book specification of audio CDs, they are not read by all CD players, which prevents some devices from reading CD-Text information.
Format.
MMC-3 specifies 16 types. Of these, three are reserved and therefore they don't have keywords.
The character encoding is not specified, and there is no provision for indicating in the CD-Text data which encoding is in use. The original Sony authoring tools and specifications supported ASCII and two of its supersets, ISO-8859-1 and "MS-JIS". Annex J of the MMC-2 specification mentions only ASCII, but provides for "double byte character codes" to be indicated.