Sparable area

An important part of the UDF File System.
As of UDF 1.5 CD-RW / DVD+-RW can contain a Sparable area.
This sparable area is used to do defect management on host level.

For drives that have defect management on board (e.g. Mount Rainier, MRW) no host defect management is necessary and applications use UDF 1.02 again which doesn't have a sparable area.