Sets options for DWG files and for drawing interchange file output.
The following options are displayed.
DWG Options Tab (Saveas Options Dialog Box)
Controls the drawing index and display of custom objects and specifies the default file format for saving drawings.

Save Proxy Images of Custom Objects
If you save to an earlier drawing file type, or the drawing contains custom objects from another application, you can select Save Proxy Images of Custom Objects to save images of the custom objects in the drawing file. If you do not choose this option, a frame is saved for each custom object in the drawing file. (PROXYGRAPHICS system variable)
Specifies the default file format that drawings are saved to. If you change the specified value, all subsequent uses of SAVE and QSAVE save the drawing to the new file format. You can also set this option on the Open and Save tab in the Options dialog box (see OPTIONS). Set the Save As option to AutoCAD 2007 Drawing to optimize performance while saving.
DXF Options Tab (Saveas Options Dialog Box)
Sets drawing interchange file output options.

Specifies whether the program creates an ASCII or a binary DXF file. ASCII-format DXF files can be read with a text editor and are compatible with a wider range of applications. Binary-format DXF files contain all of the information of an ASCII DXF file but in a more compact form. You can read and write to binary-format files faster than to ASCII-format files.
For more information about DXF files, see the DXF Reference in the Help system.
Specifies whether an image of the drawing is displayed in the Preview area of the Select File dialog box (RASTERPREVIEW system variable).
Saves the file using the specified number of bits of precision. The default precision is adequate in most cases; however, you might need to increase this value for certain drawings and for certain applications. If you encounter problems loading a DXF file you create, try increasing the precision. The only disadvantage of higher precision is increased file size.