| DXF
|
DXF is the external format for AutoCAD, and is a test-based representation of the AutoCAD database. If an item is not in AutoCAD it is not in DXF. Some companies talk of "extended DXF" but we only recognize AutoCAD's definition. DXF is fairly stable between different releases of AutoCAD, although new items are continually added to the specification as new entities are added to AutoCAD. |
| Binary DXF
|
Binary DXF is a semi-binary form of the DXF format. The item labels are stored as null-terminated text strings and the group codes, integer and floating point numbers are stored in binary format. Binary DXF can represent everything that is in a normal DXF file. Binary DXF is not supported by most programs but can be read just like a normal DXF file into AutoCAD. |
| DWG
|
DWG is the internal binary database format for AutoCAD. Autodesk does not publish the DWG file format information. Some companies have reverse engineered the file format. DWG is now being supported by certain non-AutoCAD systems in the same manner that DXF is supported by non-AutoCAD systems: as a secondary format, not the native database format. |
| HPGL |
The Hewlett-Packard Graphics Language (HP-GL) was developed over a number of years by the Hewlett-Packard Corporation for use in their line of plotters. HP-GL has become a de-facto standard for plotter formats and is supported by almost all plotter manufacturers as a standard emulation. Most CAD systems have the capability of outputting HP-GL. |
| HPGL2 |
Since HP-GL was added to rather haphazardly over the years as plotter technology increased, not all HP-GL plotters can read all HP-GL files completely. In 1990 Hewlett-Packard standardized the different versions of HP-GL as HP-GL/2. While doing so they also enhanced the specification to allow a more compact form (Encoded Polylines) that greatly reduces file size. |
| Computer Graphics Metafile (CGM) |
CGM is the international standard for graphic images. It is a neutral format that is mainly for "presentation" type graphics. It is not intended as a CAD format. It is a very rich format but implementations are often incompatible with one another. We support CGM as an output format only. We support six different files or flavors of CGM: standard, two MIL SPEC variations, two Air Transport Association variations and ActiveCGM (which is designed for use on the World Wide Web). We also allow the use of either Real or Integer format and binary, clear text and character encoding. |
| Drawing Web Format
|
DWF is AutoDesk's answer for a simple vector format for the World Wide Web. We now support Version 3 of DWF which adds support for layers and full definition of polylines. Version 2 added support for arcs, circles, ellipses and text. Previously we were limited to line segments due to limitations of AutoDesk's DWF file viewer. With the improved entity set of Version 2, file size is now reduced by a factor of 6 on a typical drawing. |
| Simple Vector Format
|
SVF is NCSA/SoftSource's answer for a simple vector format for the World Wide Web. It is the most mature of the three web formats (defined originally in 1994) but with the de-emphasis of NCSA as the driving force behind the web (they developed Mosaic, but recently they have been relegated to "also-ran" status) the future of SVF is murky. SoftSource does offer a Netscape Plug-In for viewing SVF files (http://www.softsource.com/). |
| Postscript
|
Postscript was developed by Adobe Systems as a full featured programming language that is used to describe output for printing and, now, for display. It is based on the language Forth. It uses postfix notation where the parameters precede the operation. For instance, to draw a line to point (10,10) the command 10 10 lineto is used. Normally PostScript is used to describe the layout of objects on a page. These objects can be geometrical elements like lines, arcs and Bezier curves, text elements or raster images. There are no primitives for entities like circles and ellipses but they can be defined using arcs or Bezier curves. |
| Illustrator
|
It is sort of ironic that Adobe Illustrator, the drawing package for Macintosh and Windows-based computers from Adobe, the developers of PostScript, cannot directly read PostScript files. Adobe Illustrator uses a PostScript file with specially formatted headers and footers. These headers and footers vide definitions for the shorthand notation that Adobe Illustrator defines so other PostScript interpreters can understand the file. Of course, Adobe Illustrator does not need the information in the headers and footers to understand the file format Adobe Illustrator's shorthand notation for commands (for instance to draw a line to (10,10) the command is 10 10 L instead of 10 10 lineto) which greatly reduces file size. Part of the header information is a redefinition of the L commands to be the same as lineto. Unfortunately, Adobe Illustrator cannot read the normal PostScript commands. For instance, it only recognizes 10 10 L and not 10 10 lineto as a valid line. |
| CADL
|
CADL is Cadkey's development language. However, it doubles very nicely as an external file format. CADL is a text file with one or more lines for each entity. To read the CADL file into Cadkey use the FILES | CADL | EXECUTE option on the Cadkey menu. When listing the name of the file do not include the .CDL extension but do give the full path. |
| IGES |
The Initial Graphics Exchange Specification (IGES) is the U. S. national standard for the exchange of data between dissimilar CAD systems. The IGES standard, now in its sixth revision, has been expended to include most concepts used in major CAD systems. All major and most minor non-PC based CAD systems support some version of the IGES standard. Some of the over 1000 PC-based CAD systems (including all of the major ones) include some IGES support. IGES is intended as a "neutral" format, not tied to any particular CAD system. IGES is an ASCII text-based format formatted in 80 column card images. |