The Gerber format is an open ASCII vector format for printed circuit board (PCB) designs. It is the de facto standard used by PCB industry software to describe the printed circuit board images: copper layers, solder mask, legend, drill data, etc. The official website contains the specification, test files, notes and the Reference Gerber Viewer to support users and especially developers of Gerber software. There are two major generations of Gerber format: The standard file extension is .GBR or .gbr though other extensions like .GB, .geb or .gerber are also used.