MicroStation line styles are similar to AutoCAD linetypes. The MicroStation line style definitions are stored in line style libraries, which are attached as needed to the active model. You can customize line styles using the Line Style Editor, and save the new definitions to the line style library.

In AutoCAD, linetypes are also stored in an external text file, but only the linetypes used in the current model/layout are loaded into the DWG file and stored there. New linetypes can be created using a text editor and then stored externally. However, while DWG complex linetypes can contain text from SHX files and shapes defined in SHX shapefiles, they cannot use complex geometry (splines, cells, etc.) as they can in MicroStation. Furthermore, AutoCAD only supports a single spacing option, and does not support dash widths, tapering, and other options available for MicroStation line styles. For this reason, MicroStation custom line styles are not compatible with AutoCAD.

When you import and save a DGN file as a DWG file in AutoCAD, the line styles are embedded in the DWG file. Depending upon how these line styles were created in the original DGN file, you may have the following results when you open the DWG file back in MicroStation:

• DGN Standard line styles — these are named as DGNx in DWG line type table, where x denotes the DGN line code 0 through 7. These DWG line types do not have a constant dash-dot size and are independent of the zooming factor. Therefore, when you open a DWG file, entities that use these line styles are re-assigned to MicroStation’s standard line styles 0 through 7. The original DWG line styles are still kept in the file unused.
• Custom line styles that come from a line style RSC file — When an RSC file is available in the folder pointed by the MS_SYMBRSRC configuration variable, MicroStation looks up for the line style name in that RSC file. If the name is found, the line style data is imported from the RSC file for the DWG line style. Entities using these line styles look the same as they look when using the RSC file’s line styles.
• Custom line styles that come from a DGN file — The custom line styles that are saved in the DGN file and not in the RSC file cannot be accessed and are ignored. You can see the names of these ignored line styles in the Message Center. Entities that use these line styles appear as solid lines.