Universal Disk FormatUDF: Universal Disk Format is a CD-ROM and DVD file system standard used to ensure compatibility across platforms, as well as among various CD and DVD application via the ISO/IEC 13346 standard. UDF is required for DVD-ROMs, and is used by DVD to contain MPEG audio/video streams. Originally developed as a replacement for ISO 9660, UDF is used by CD-R and CD-RW in a process called packet writing (Drag-to-Disc) that makes CD writing more efficient with disk space.A "Bridge" is simply a combination of any two standards.