"The third mode, Virtual, takes some getting used to. Using
virtual folders lets you organize your DVD catalog more logically.
Suppose you have six discs that contain the digital photos of your
last trip all indexed inside a single "Japan 2008 images" virtual
folder. If you edit some of the images, for example removing some
red eye, and burn the updated images to a new disc later, you can
then add those images to the same Japan 2008 images virtual folder,
even though they might be on a DVD you burn two years later."