Blu-ray is a high-density optical multimedia format disc for the storage of digital information, including high-definition video.
Blu-ray Disc (BD) is a next-generation optical disc format designed for high-density storage of high-definition video and data. The offical homepage of the Blu-ray Disc Association is http://www.blu-raydisc.com. There are some public available technical white papers under http://www.blu-raydisc.com/Section-13470/Section-13628/Index.html . For the filesystem used on ths media have a look at the UDF 2.5 and 2.6 specification at http://osta.org/specs/