To Set Up a GDC File

To set up a new grid data file

1. When you obtain a new grid data file, copy it into the appropriate folder under the Autodesk shared coordinate system folder. For Windows XP, the default location is C:\Documents and Settings\All Users\Application Data\Autodesk\Geospatial Coordinate Systems. For Windows Vista and Windows 7, the default location is C:\Users\AllUsers\Autodesk\Geospatial Coordinate Systems.
2. Open the appropriate GDC file in any text editor or word processor that can produce an ASCII file, such as Notepad or Wordpad.
   Note:

   Back up GDC files before you edit them, so you can restore them to their previous state, if necessary.

3. Edit the file to point to the name and location of your new grid data file.
4. Make other changes needed, such as rearranging or replacing grid data files, changing the fallback datum definition, or adding comments.