# CD+EG **Wikidata**: [Q5155272](https://www.wikidata.org/wiki/Q5155272) **Wikipedia**: [English](https://en.wikipedia.org/wiki/Compact_Disc_+_Extended_Graphics) **Source**: https://4ort.xyz/entity/cd-eg ## Summary CD+EG (Compact Disc + Extended Graphics) is a subclass of optical disc defined by its ability to store extended graphics data alongside audio. Also known as CD+XG, it functions as a machine-readable medium that encodes binary data on a flat, circular polycarbonate substrate, adhering to the physical and technical standards of the optical disc family. ## Key Facts * **Aliases:** Compact Disc + Extended Graphics, CD+XG. * **Classification:** Subclass of **optical disc**; categorized under optical storage, machine-readable media, and removable media. * **Physical Form:** Flat, circular disk, most commonly 120 mm in diameter, with an 80 mm "mini" version existing. * **Data Encoding:** Stores binary data as microscopic pits and lands read by a laser. * **Material Composition:** typically consists of a polycarbonate substrate, a reflective layer (aluminum or gold), and a protective lacquer coating. * **Wikipedia Title:** "Compact Disc + Extended Graphics" (English). * **Contextual Family:** Belongs to the optical disc ecosystem, which includes formats like CD, DVD, Blu-ray, and specialized variants like CD+G and M-Disc. ## FAQs ### What is CD+EG? CD+EG (Compact Disc + Extended Graphics) is a specific format of optical disc. It is structurally a flat, circular medium that uses laser-readable pits and lands to store binary data, classifying it as a type of optical storage and removable media. ### How is CD+EG classified within storage media? It is a subclass of the optical disc. This places it within the broader categories of machine-readable mediums, computer storage media, and optical storage. ### What materials make up a CD+EG? As an optical disc, it is physically composed of a polycarbonate substrate bonded to a reflective layer (typically aluminum or gold) and sealed with a protective lacquer coating. ### What are the standard dimensions for this format? CD+EG follows the standard physical dimensions of the optical disc family, primarily 120 mm (approximately 4.7 inches) in diameter, though an 80 mm "mini" version is also part of the standard classification. ## Why It Matters CD+EG represents a specialized evolution within the optical disc ecosystem, expanding the utility of the standard Compact Disc format. As a subclass of optical media, it inherits the revolutionary traits of the format: the ability to distribute data physically without requiring power to retain it and the durability necessary for long-term usage. The existence of "Extended Graphics" variants demonstrates the flexibility of the optical disc platform, allowing it to adapt from simple audio playback to more complex audiovisual applications. While streaming and solid-state storage have grown, formats like CD+EG remain relevant for offline distribution and as part of the diverse historical ecosystem of optical media that includes CDs, DVDs, and Blu-ray. ## Notable For * **Extended Graphics:** Specifically identified by its capacity for extended graphics, distinguishing it from standard audio CDs. * **Nomenclature Variants:** Notable for having the alias **CD+XG**. * **Optical Heritage:** Being a direct descendant of the Compact Disc (introduced 1979), leveraging the same laser-reading technology and physical form factor. * **Ecosystem Diversity:** Illustrates the wide range of specialized optical formats (alongside CD+G, MP3 CD, etc.) that served specific niche uses in digital media. ## Body ### Definition and Classification CD+EG (Compact Disc + Extended Graphics), also aliased as CD+XG, is a specific format of digital storage media. Structurally and functionally, it is a **subclass of the optical disc**. As such, it falls under the broader taxonomic categories of optical storage, machine-readable mediums, and computer storage media. It is defined by its physical characteristics as a removable medium that encodes binary data, typically used for data distribution. ### Physical Characteristics and Technology As a member of the optical disc family, CD+EG shares the standard physical and technological properties of the medium: * **Geometry:** The format is flat and circular. The standard diameter is **120 mm** (≈ 4.7 in), though the optical disc family also includes an **80 mm** (≈ 3.1 in) "mini" version. * **Construction:** The disc is built upon a **polycarbonate substrate**. Data is physically encoded into this surface as microscopic **pits (depressions)** and **lands (flat areas)**. * **Reading Mechanism:** A low-power laser in an optical disc drive reflects off the pits and lands. The variations in reflected light are interpreted by the drive as binary 0s and 1s. * **Layers:** The data layer is covered by a reflective layer of aluminum or gold and protected by a lacquer coating. ### Historical and Ecosystem Context CD+EG exists within the timeline of optical disc development, which began commercial adoption with the LaserDisc (1978) and the Compact Disc (1979). * **Format Family:** It is part of the diverse ecosystem of optical formats that evolved from the original CD standard. This ecosystem includes major families like DVD (introduced 1995) and Blu-ray (introduced 2006), as well as specialized variants. * **Specialized Variants:** The source material identifies "CD+G" (Compact Disc + Graphics) as a related specialized variant used for graphics. CD+EG (Extended Graphics) functions within this specific category of enhanced optical discs. * **Usage:** Like other optical discs, CD+EG is designed to be read by optical disc drives integrated into computers, game consoles, or standalone players. ### Identifiers and Standards * **Wikipedia Title:** Compact Disc + Extended Graphics. * **Wikipedia Languages:** Available in English (sitelink count: 1). * **Unicode Context:** While specific Unicode symbols for CD+EG are not listed, the parent category of optical disc is represented by 💿 and 🖸.