Source : Free On-Line Dictionary of Computing

Universal Disk Format
     
         (UDF) A {CD-ROM} {file system} {standard}
        that is required for {DVD ROMs}.  UDF is the {OSTA}'s
        replacement for the {ISO 9660} file system used on CD-ROMs,
        but will be mostly used on DVD.  {DVD multimedia} disks use
        UDF to contain {MPEG} {audio} and {video} {streams}.
     
        To read DVDs you need a DVD drive, the {kernel} driver for the
        drive, MPEG video support, and a UDF driver.  DVDs containing
        both UDF filesystems and ISO 9660 filesystems can be read
        without UDF support.
     
        UDF can also be used by {CD-R} and {CD-RW} recorders in
        {packet writing} mode.
     
        (1999-09-01)