RS274X

RS-274X is the extended version of the Gerber format used to describe printed circuit board artwork and other fabrication data. It is the de facto standard for communicating copper features, solder mask, silkscreen, and other layer information to PCB manufacturers, and it supersedes the earlier RS-274-D format. The X designation reflects enhancements such as embedded aperture definitions and aperture macros, which allow complex shapes to be defined within a single file without relying on external libraries.

Key features of RS-274X include embedded aperture definitions and aperture macros for flexible geometry, as well as support for region mode to create filled polygons. It provides explicit handling of coordinates and units, with options for decimal precision and a choice between absolute or incremental coordinates. The data stream uses a compact set of commands for moving, drawing, and flashing apertures, along with aperture selection and a file termination marker.

In typical PCB workflows, each layer—copper, solder mask, and silkscreen—is exported as a separate RS-274X file. Drill data are supplied separately in the Excellon format; together, these files convey the complete fabrication data for a board. RS-274X remains widely supported by CAM software and PCB fabricators and continues to be a central format for traditional data exchange.

Limitations of RS-274X include the need for capable parsers to handle macros and region-based features, and potential increases in file size for complex boards. Despite these considerations, its widespread adoption and well-defined semantics have sustained its prominence, even as newer extensions and metadata schemes to enhance documentation and automation have emerged.