The Gerber file is an image format used to print CAD layer drawings on film with a specialized PCB film plotter,or on photo-resist with a direct imaging printer. Gerber RS-274X is the PCB Industry Standard file format. An output file is generated for each layer in your project. These files are ASCII and can be viewed with any text editor.
The data has two variants:
- RS-274-D (depreciated) AKA Standard Gerber
- RS-274X (AKA Extended Gerber, AKA Enhanced Gerber)
Extended Gerber is a richer format that has all the constructs necessary for describing a PCB image efficiently. It has regions, positive/negative levels and powerful aperture macros. Planes and anti-pads can be described without painting. Pads are properly described as flashes, ensuring that no data is lost. RS-274-D files do not contain embedded aperture data. A fixed Aperture File or D-code Table is used during the generation stage of the CAD output, and must be included with your data package.
- 7.8 Revoked Standard Gerber (RS-274-D)
The current Gerber file format is also known as RS-274X or Extended Gerber. There is also a historic format called Standard Gerber or RS-274-D format. Standard Gerber is revoked and superseded by Extended Gerber, which is the current Gerber format. Consequently, Standard Gerber no longer complies with the Gerber specification. Files in that format can no longer be correctly called Gerber files. Standard Gerber files are not only deprecated, they are no longer valid. Standard Gerber is technically obsolete, revoked and superseded by RS-274X.
It differs from the current Gerber file format (RS-274X), in that it:
- does not support G36 and G37 codes
- does not support any extended codes
Standard Gerber does not allow defining the coordinate format and aperture shapes. It is incomplete as an image description format. It lacks the imaging primitives needed to unequivocally transfer information from PCB CAD to CAM The word “standard” is misleading here. Standard Gerber is standard NC format. It is not a standard image format: image generation needs a so-called wheel file, and that wheel file is not governed by a standard. The interpretation of a wheel files, and consequently of a Standard Gerber files, is subjective. In Extended Gerber (RS-274X) image generation is fully governed by the standard. Extended Gerber is the true image standard. Standard Gerber has major drawbacks compared to the current Gerber file format and does not offer a single advantage. Standard Gerber is obsolete. There is not a single valid reason to use standard Gerber rather than Extended Gerber. Always use Extended Gerber (RS-274X). Never use Standard Gerber.
Warning: The responsibility of errors or misunderstandings about the wheel file when processing a Standard Gerber file rests solely with the party that decided to use revoked Standard Gerber, with its informal and non-standardized wheel file, rather than Extended Gerber, which is unequivocally and formally standardized.