DvdDao: formatting dvd-rw media

Does anyone understand the point of the DvdDao '--format DvdRwFull' and
'--format DvdRwQuick' options for formatting DVD-RW (minus) media? I
understood that this was to convert DVD-RW from its default incremental
sequential mode to restricted overwrite mode. But when I tried it, it
turns out that either option does a long (30 minute) format and produces an
empty disk that has 0 bytes free. I find it hard to see what this is good

DVD+RW media is working well for me for backups, and is really convenient. I
have to do a one-time format on virgin media using the '--format DVD+RW'
command. This takes only a minute. I have an xcopy2dvd script that runs
EABackup, MkIsoFs with switches to allow pretty much any HPFS filenames, and
pipes it right into DvdDao. This makes it really easy to simply 'xcopy' an
directory tree or entire partition onto any available DVD+RW disk (I keep my
partitions smaller than DVDs hold). The 'xcopy' works fine even if the disk
was previously used. It simply overwrites the previous contents, with no
need to do any new formatting. If I had never heard of DVD-RW media, I'd be
happy. But I have a bunch of DVD-RW disks too.

DVD-RW media also works for me for backups, and is arguably safer. I can run
my script on virgin DVD-RW media without any preparation at all. But I can't
overwrite a disk without first using the '--blank fast' command, at least.
OK, I can live with that. It might even protect me from blindly overwriting
my only backup.

But that still leaves the question of *why* DVDDAO includes not only the
options to blank DVD-RW media and format DVD+RW media, but also separate
options to format DVD-RW media. In every test I have been able to think of,
this results in an empty disk with 0 bytes free. It did occur to me that
maybe DVDDAO simply can't write to a DVD-RW disk that has been formatted to
restricted overwrite mode. But if that's the case, it doesn't make much
sense to include the formatting option. What am I missing here? (Besides a
manual for DVDDAO?)

Walt Gregg (walt at w-gregg dot juneau.ak.us)