Is the blu ray spec comprehensive enough to support professional data archival (like the defunct Sony PDD targeted)? I'm sure the shelf life of any optical recordable media should be OK(?). WORM media needs to be supported. What legally constitutes WORM, I don't yet know. For instance: one can "delete" from CD-R and DVD-R making them not WORM to the degree required for professional archival? Was there a special feature in PDD that made this impossible to do?