Got this from Ultimate AV mag
No matter how much data storage is available in any medium, people always want more. Take Blu-ray, for example—one might think that 25 or 50GB would be plenty for just about any storage requirement, but some applications need even more. To address this insatiable demand, the Blu-ray Disc Association this week announced a new high-capacity recordable format called BDXL as well as a new hybrid format called IH-BD.
rest of topic found at...
http://www.ultimateavmag.com/news/new_blu-ray_formats_introduced/