Use this dialog box to set options when you export data to Microstation Design (DGN7).
Select the coordinate units of the features: Master or Sub.
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).
Select the seed file, which controls whether or not the output DGN file is two-dimensional or three-dimensional, sets the coordinate units, sets global origin, and more. For DGN version 7, you must use a version 7 DGN seed file.
Override the global origin setting in the seed file. Specify the global origin to use.
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.