Save drawing files for later use just as you do with other applications. You can also set up automatic saving and backup files and save only selected objects.
When you work on a drawing, you should save it frequently. Saving protects you from losing work in the event of a power failure or other unexpected event. If you want to create a new version of a drawing without affecting the original drawing, you can save it under another name.
The file extension for drawing files is .dwg, and unless you change the default file format in which drawings are saved, drawings are saved in the latest drawing file format. This format is optimized for file compression and for use on a network.
If you share drawing files with offices or companies in other countries and regions, the drawing file names might contain characters that are not used in other languages.
In either case, you will be able to open the drawing file in AutoCAD 2007 because the product is Unicode compliant.