<P> The BDXL format allows 100 GB and 128 GB write - once discs, and 100 GB rewritable discs for commercial applications . It was defined in June 2010 . BD - R 3.0 Format Specification (BDXL) defined a multi-layered disc recordable in BDAV format with the speed of 2 × and 4 ×, capable of 100 / 128 GB and usage of UDF2. 5 / 2.6 . BD - RE 4.0 Format Specification (BDXL) defined a multi-layered disc rewritable in BDAV with the speed of 2 × and 4 ×, capable of 100 GB and usage of UDF2. 5 as file system . </P> <P> The IH - BD (Intra-Hybrid Blu - ray) format includes a 25 GB rewritable layer (BD - RE) and a 25 GB write once layer (BD - ROM), designed to work with existing Blu - ray Discs . </P> <P> Blu - ray Disc specifies the use of Universal Disk Format (UDF) 2.50 as a convergent friendly format for both PC and consumer electronics environments . It is used in the latest specifications of BD - ROM, BD - RE, and BD - R. In the first BD - RE specification (defined in 2002), the BDFS (Blu - ray Disc File System) was used . The BD - RE 1.0 specification was defined mainly for the digital recording of high - definition television (HDTV) broadcast television . The BDFS was replaced by UDF 2.50 in the second BD - RE specification in 2005, in order to enable interoperability among consumer electronics Blu - ray recorders and personal computer systems . These optical disc recording technologies enabled PC recording and playback of BD - RE . BD - R can use UDF 2.50 / 2.60 . </P> <P> The Blu - ray Disc application for recording of digital broadcasting has been developed as System Description Blu - ray Rewritable Disc Format part 3 Audio Visual Basic Specifications (BDAV). The requirements related with computer file system have been specified in System Description Blu - ray Rewritable Disc Format part 2 File System Specifications version 1.0 (BDFS). Initially, the BD - RE version 1.0 (BDFS) was specifically developed for recording of digital broadcasts using the Blu - ray Disc application (BDAV application). But these requirements are superseded by the Blu - ray Rewritable Disc File System Specifications version 2.0 (UDF) (a.k.a. RE 2.0) and Blu - ray Recordable Disc File System Specifications version 1.0 (UDF) (a.k.a. R 1.0). Additionally, a new application format, BDMV (System Description Blu - ray Disc Prerecorded Format part 3 Audio Visual Basic Specifications) for High Definition Content Distribution was developed for BD - ROM . The only file system developed for BDMV is the System Description Blu - ray Read - Only Disc Format part 2 File System Specifications version 1.0 (UDF) which defines the requirements for UDF 2.50 . </P>

What type of file system is used by blu-ray discs