Using a Command Prefix
The configuration variable MS_DWG_COMMANDPREFIX can be set to a character or string of characters that can be used as a shortcut to the AutoCAD commands. Any key-in that begins with this shortcut will be matched first to the command aliases as defined in a PGP file, and then to the DWG commands.
The default prefix is the backslash character (\), but other characters or sequences may also be used. The space character may be a convenient prefix due to its keyboard location. Avoid using a prefix that could be interpreted as a MicroStation key-in. For example, using AC as the prefix conflicts with the key-in for MicroStation key-ins such as ACTIVE ANGLE.
When defining a prefix, enclose the definition within double quotes to avoid having it misinterpreted (use \ rather than \ ).
To use the command prefix in a DGN file, add the MDL application dwgsettings.ma to the MS_DGNAPPS configuration variable.