The Importance of Being DWG
To take full advantage of AutoCAD in your work environment, you need to be aware of the DWG file format, the format in which AutoCAD saves drawings. Here are some DWG facts to keep in mind:
- In some cases, an older release of AutoCAD can't open a DWG file that's been saved by a newer AutoCAD release.
- A newer release of AutoCAD can always open files saved by older versions.
- Some previous AutoCAD releases can open files saved by the subsequent one or two versions. For example, AutoCAD 2007 and AutoCAD 2008 can open DWG files saved by AutoCAD 2009. That's because Autodesk didn't change the DWG file format between those releases. However, the drawing file format did change with AutoCAD 2010, so drawings created in the current release must be saved in an older format to be openable in AutoCAD 2009 and earlier.
- You can use the Save As option in newer releases to save the file to some older DWG formats. In fact, AutoCAD 2012 can save as far back as AutoCAD Release 14, which dates all the way back to 1997!
Table 1-1 shows which versions (described later in this chapter) use which DWG file formats.
Table 1-1 AutoCAD Versions and DWG File Formats
The new file format introduced in AutoCAD 2010 was necessary to handle new features — especially parametric drafting, and that format proved more efficient at saving files and handling much larger objects. Best of all, from the user's perspective, it was noticeably faster to work with than AutoCAD 2009.
Working with AutoCAD is easier when your co-workers and colleagues in other companies all use the same release of AutoCAD and AutoCAD-related tools. That way, your DWG files, add-on tools, and even the details of your CAD knowledge can be mixed and matched among your workgroup and partners. In the real world, you may work with people, probably from other companies, who use AutoCAD releases as old as AutoCAD 2006 — or even older.
Many programs claim to be DWG-compatible — that is, capable of converting data to and from the AutoCAD DWG format. Achieving this compatibility is, however, a difficult thing to do well. Even a small error in file conversion can have results ranging in severity from annoying to appalling. Every time you open a drawing file, AutoCAD checks its parentage and warns you if the drawing was created by a non-Autodesk program. If you exchange DWG files with people who use other CAD programs, you may have to spend time finding and fixing translation problems.