How is an HD DVD-ROM disc constructed?
Similar to conventional DVD-ROM construction, an HD DVD-ROM (prerecorded) is a sandwich of multiple layers of materials with either one or two data sides (single or double-sided) each with one or two data layers (single or dual-layer). A single-sided (SS) disc is composed of a data side and a dummy side while a double-sided (DS) disc consists of two data sides.