Hope this Info from a vendor helps Gerber files A PCB is fabricated as a series of layers that the manufacturer assembles into a board through a variety of chemical and mechanical processes. To fabricate each physical layer in the PCB the manufacturer uses an image of that layer -- this image is referred to as a phototool. A phototool is a piece of clear film, with black lines, circles and other shapes forming exactly the same patterns as the content of that layer in AutoTRAX. Gerber data is a simple, generic means of transferring printed circuit board information to a wide variety of devices that convert the electronic PCB data to artwork produced by a photoplotter. Virtually every PCB CAD system generates Gerber data because all photoplotters read it. It is a software structure consisting of X,Y coordinates supplemented by commands that define where the PCB image starts, what shape it will take, and where it ends. In addition to the coordinates, Gerber data contains aperture information, which defines the shapes and sizes of lines, holes, and other features. Gerber Format, which is the format in which Gerber data is expressed, actually is a family of data formats that are subsets of EIA Standard RS-274D. Extended Gerber Format, which is also called RS-274X, provides enhancements that handle polygon fill codes, positive/negative image compositing, and custom apertures, and other features. RS-274X also encapsulates the aperture list in the header of the Gerber data file and therefore allows files to pass from one system to another without the need to re-input the aperture table. RS-274X produces a variety of Gerber data called X data. RS-274X is a superset of the EIA Standard RS-274D format. RS-274X supports some of the parameter data codes (G codes) and aperture codes (D codes) contained in RS-274D, as well as codes referred to as mass parameters. Mass parameters are plot parameters that define characteristics that can affect an entire plot, or only specific parts of the plot, called layers. Mass parameters extend the capabilities of Gerber Format. Their presence makes the Gerber data X data. RS-274X is maintained by Gerber Systems Corporation (GS), a leading supplier of CAD/CAM systems, large-area plotting systems, and precision cutting systems since 1965. An RS-274X plot file is a file consisting of RS-274X parameters and standard RS-274D codes which, when correctly interpreted, result in an image that may be displayed or plotted. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------