Used to create a backup file of the active, open DGN file.

Backup files are created and saved in the default project directory and the status bar displays the location, backup file name, and backup file extension, of the saved file.

The backup file is named with the same file name, and receives a *.b1 file extension. If a backup file already exists, the new backup file receives a *.b2 file extension, and so on. When the maximum number of successive backup files is reached, the oldest file is deleted. The Successive Backups setting (in the Preferences dialog, Building Designer Category) can be used to specify the maximum number of successive backups.