What is a seed file?
A seed file is a CAD drawing that is used in its native format as an input parameter with the Export To CAD tool. It functions as a template and provides base data for the destination CAD file.
You can use a seed file to store layer names, styles, and other common settings. By default, the Export To CAD tool exports features to layers in the seed file that are named the same as the input feature layer name or feature class name, when they exist. You can also use seed files to store user-defined CAD objects such as AutoCAD block definitions and reference them individually during execution using reserved CAD fields.
MicroStation DGN V8 files require a 2D or 3D seed file that is consistent with the input features. 3D data is identified by the presence of z-values. Use the Feature Class Properties dialog box to make this determination. The default DGN seed files used by the Export To CAD tool are located in the ArcToolbox templates folder (example: C:\Program Files\ArcGIS\Desktop10.0\ArcToolbox\Templates\).
Formats and versions
You create seed files using the native CAD application for the destination format. The seed file format and version must match the format and version of the destination CAD file.
Seed file format
DWG and DXF
DWG or DWT