http://www.hughsnews.ca/faqs/authoritat ... ations#4.9
. . . . BD9 employs the same file system (UDF 2.5), content protection (AACS, BD+, ROM Mark) and structure (BD-ROM AV HDMV/BD-J) used by commercial BD-ROM movies.
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As such BD9 offers identical features to BD-ROM although there are some restrictions (transport stream maximum data rate 28 Mbps vs. 48 Mbps) arising from its somewhat lower performance (user data rate 33.24 Mbps vs. 53.948 Mbps)