Physical CD formats

Philips and Sony as the inventors of the CD have defined the physical structure of CD in a small set of standards, the (red, yellow, green, and orange books). Two of these standards are of relevance for data CDs:

CD-ROM DA

is the original audio CD for up to 74 minutes of 16 bit audio signals sampled at 44.1kHz. This format is also suited for other types of data. It is described in the red book.

CD-XA

is a multisession format in which data can be written to the CD in a sequence of sessions. CD-XA is described in the yellow book.

The CD-XA format has now almost completely replaced the DA format for the storage of data, even if data is written in one session only.

The green and orange books are for CD-i and CD-R respectively.