I saw a discussion once about the invisible files that older versions
of Toast adds to the burn. They can be seen by looking at the data
before burning, but they are invisible on the burned disk. In older
versions of Toast like the 3.5.6 that I have, they can't be deleted
before burning. Since one of these is the HD's desktop file, this
could compromise security if someone who possesses the burned disk digs
it out with a utility.
The advice given was to upgrade to a newer version of Toast where
there's a choice to not burn these ...