Drawing standards (DWS) files are used by the CAD Standards and Batch Standards Checkers in addition to storing layer mappings used by the Layer Translator.
If you create a new drawing standards (DWS) file, it is saved in the native drawing file format for the release in which it is created. If you make changes to a DWS file that might need to be used with an earlier release, you will need to save the DWS file as a drawing file in the earlier drawing file format and then change its file extension in Windows Explorer or File Explorer from .dwg to .dws.