Select the unit that matches the default unit in your AutoCAD Map 3D drawing. For example, if the default unit in your AutoCAD Map 3D drawing is meters, and you are using a seed file that defines meters as the Master unit, then select Master (the default).
Override all seed file settings and have AutoCAD Map 3D calculate the settings for you. AutoCAD Map 3D determines the largest dimension for the set of exported objects and sets the appropriate range and precision. It sets the UOR per Sub to 10, and sets the Global Origin to the center of the bounding rectangle of the exported objects.