The specification for the write-once DVD-R disc, DVD-R (3.95 GB) Book version 1.0 was released in 1997, and Pioneer began selling industrial DVD-R discs and drives that same year. A preliminary specification for a 4.7 GB disc, Book version 1.9, was released in November 1998. However, as a result of discussions about issues related to copy protection, the 4.7 GB DVD-R specification was divided into two specifications, DVD-R for Authoring version 2.0, and DVD-R for General version 2.0, which were published in February and May of 2000, respectively. Following that, supplemental information documents were published as addendums to the General specification in September and December of 2000, bringing the DVD-R specification to the form in which it exists today.
The specification for the rewritable DVD-RW disc, on the other hand, targeted a 4.7 GB capacity from the start. Version 1.0 of that specification was published in November 1999. In September of 2000 revision information was released to bring the specification to version 1.1, with a supplemental information addendum also published in September and December, bringing that specification to the form in which it exists today.
The content of those specifications will be described later in this chapter. A broad range of DVD-R discs, DVD-RW discs, DVD recorders, and DVD-R/RW drives based on these specifications are now being introduced to the market.

II.Basic Concept

The basic concept behind DVD-R and DVD-RW are now well-known. The most fundamental concept is that these discs are compatible with read-only DVD discs. This is exactly equivalent to the relationship between CD-ROM discs, and CD-R and CD-RW discs. The basic discs are high-volume pressed versions, with compatible recordable media also playing a major role. Therefore, the 4.7 GB DVD-R disc is specified such that after recording, its signal characteristics and format of the recorded data are the same as those defined by the DVD-ROM specification. The same is true of DVD-RW; with the exception that the reflectivity of DVD-RW discs are the same as that of dual-layer DVD-ROM discs, DVD-RW discs are like DVD-R discs with the addition of rewrite capability.
Since all these specifications are defined based on this fundamental concept, DVD-R and DVD-RW discs can be easily played in players designed for read-only DVDs and in DVD-ROM drives.