.dwg
| Filename extension |
.dwg (plain).dws (standards).dwt (template) |
|---|---|
| Internet media type |
|
| Developed by | Autodesk, Open Design Alliance and others |
| Initial release | 1982 |
| Type of format | Computer-aided design |
| Open format? | No |
DWG (from drawing) is a proprietary binary file format used for storing two- and three- dimensional design data and metadata. It is the native format for several CAD packages including DraftSight, , IntelliCAD (and its variants), Caddie and Open Design Alliance compliant applications. In addition, DWG is supported non-natively by many other CAD applications. The .bak (drawing backup), .dws (drawing standards), .dwt (drawing template) and .sv$ (temporary automatic save) files are also DWG files.
DWG (denoted by the .dwg filename extension) was the native file format for the Interact CAD package, developed by Mike Riddle in the late 1970s, and subsequently licensed by Autodesk in 1982 as the basis for . From 1982 to 2009, Autodesk created versions of AutoCAD which wrote no fewer than 18 major variants of the DWG file format, none of which is publicly documented.
The DWG format is probably the most widely used format for CAD drawings. Autodesk estimates that in 1998 there were in excess of two billion DWG files in existence.
There are several claims to control of the DWG format. As the biggest and most influential creator of DWG files it is Autodesk who designs, defines, and iterates the DWG format as the native format for their CAD applications. Autodesk sells a read/write library, called RealDWG, under selective licensing terms for use in non-competitive applications. Several companies have attempted to reverse engineer Autodesk's DWG format, and offer software libraries to read and write Autodesk DWG files. The most successful is Open Design Alliance, a non-profit consortium created in 1998 by a number of software developers (including competitors to Autodesk), released a read/write/view library called the OpenDWG Toolkit, which was based on the MarComp AUTODIRECT libraries. (ODA has since rewritten and updated that code.)
In 1998, Autodesk added file verification to AutoCAD R14.01, through a function called DWGCHECK. This function was supported by an encrypted checksum and product code (called a "watermark" by Autodesk), written into DWG files created by the program. In 2006 Autodesk modified AutoCAD 2007, to include "TrustedDWG technology", a function which would embed a text string within DWG files written by the program: "Autodesk DWG. This file is a Trusted DWG last saved by an Autodesk application or Autodesk licensed application." This helped Autodesk software users ensure that the files they were opening were created by an Autodesk, or RealDWG application, reducing risk of incompatibilities. AutoCAD would pop up a message, warning of potential stability problems, if a user opened a 2007 version DWG file which did not include this text string.
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