In DBDOC version 10.7 and earlier, the DBDOC build created a *.M14 file which you would view with Hyperview.
In newer versions of DBDOC, the build creates a *.dbdoc file instead, which is viewed with Hyperview in the same way. This *.dbdoc file has a completely different format from the older *.M14 file, so it is appropriate for it to have a different file type.
Both *.M14 and *.dbdoc files contain snapshots of your configuration at the time of the DBDOC build.
The old *.M14 files can still be handled with newer versions of DBDOC. If you ask Hyperview to display an old *.M14 file, it gives you an opportunity to open it with 10.7 Hyperview, or to abandon the request. 10.7 Hyperview is always included in newer DBDOC installations, and the 10.7 Hyperview executable (hyperview_winsock.exe) should be located in the same folder as the current Hyperview executable (hyperview.exe) in order for *.M14 files to be handled seamlessly.