Then I burned the .dmg file via Terminal with ...
Last login: Mon Nov 7 14:37:00 on ttys000
Luther-B-Fullers-Mac-mini:~ lutherfuller$ drutil -drive internal burn -noverify -eject /Volumes/Work_Files/TEST-BURN.dmg
Burning Image to Disc: /Volumes/Work_Files/TEST-BURN.dmg
Burn completed.
The resulting DVD mounted properly and contained the correct data. It also reports "A background format was started but is not currently running and is not complete.", but this seems not to cause a problem.
I was prompted to make this test after reading the drutil man page (again). It clearly states ...
burn options path
Burns a valid directory or image file to disc. The default is
to burn the specified directory to a new filesystem. ...
...
... If a file is specified (valid image files only: .dmg, .iso, .cue/bin, and .toc)
the contents of the image file are burned.
In other words, .sparsebundle files are not supported!
BUT, I've been using . sparsebundle files for years without a problem. Last week, I needed to find an old file on a backup DVD and found it on one more than a year old. So, the question now becomes ...
Why does 'drutil' no longer support .sparsebundle files? This seems very strange!