The limits of the map collar are stored in an associated FGD file. This FGD file is necessary to use the Image | Clip Image | Map Collar command. If your DRG did not come with an FGD file, it is possible to create one manually in a text editor. Open a text editor, like Notepad, and type in the West, East, North, and South bounding coordinates of the map in the format shown in the image below. Save the file to your hard drive and rename the extension to *.fgd.