XO4

XO4 is a designation used across multiple industries to label a specific model, revision, or prototype rather than a single, universal product. The combination of letters 'XO' functions as a line name or project code, while the trailing '4' typically indicates a fourth generation, revision, or version in the absence of a standard naming convention. Because XO4 can refer to different items produced by different manufacturers, it is considered a disambiguation term in many catalogs and reference works.

In electronics and consumer devices, XO4 may appear as a model number for objects such as portable players, sensors, or development boards, often accompanied by the manufacturer's branding and product family name. In software, XO4 can denote a specific build or release within a larger project, sometimes used for internal testing or feature branches. In other domains such as aerospace or automotive design, XO4 has occasionally been used as a designation for concept vehicles or experimental platforms during development phases.

When researching or citing XO4, it is important to identify the producing company, product line, and release or development date to distinguish among different instances. Without this context, the reference remains ambiguous.

See also: XO1, XO2, XO3, XO5 (designations that similarly use 'XO' as a line or project code).