Universal Disk ® Format Specification Revision 2.60 March 1, 2005 © Copyright 1994-2005 Optical Storage Technology Association ALL RIGHTS RESERVED REVISION HISTORY 1.00 October 24, 1995 Original Release 1.01 November 3, 1995 DVD appendix added 1.02 August 30, 1996 Incorporates Document Change Notices DCN 2-001 through DCN 2-024 1.50 February 4, 1997 Integrated support for CD-R and CD-RW media (DCNs 2-025 thru 2-032) 2.00 April 3, 1998 Integrated support for ECMA 167 3rd Edition which included the support for named streams. (DCN 2-033 through DCN 2-064) 2.01 March 15, 2000 Incorporates DCNs 5000, 5002, 5004, 5006-5009, 5013-5015, 5018-5021, 5024-5027, 5029-5032, 5034-5042, 5044-5048, 5050 2.50 April 30, 2003 Incorporates Metadata Partition, DCNs 5049, 5061-5066, 5068-5072, 5074-5079, 5081-5082, 5086, 5089, 5090. 2.60 January 26, 2005 Incorporates Pseudo OverWrite, DCNs 5100-5121 March 1, 2005 Approved by committee vote. Minor editorial corrections. POINTS OF CONTACT Optical Storage Technology Association UDF Technical Editor http://www.osta.org/ mailto:[email protected] Contact information OSTA UDF Committee email reflector http://www.osta.org/osta/contact.htm See link: “UDF Email Reflector” at the bottom of page: http://www.osta.org/specs/index.htm Technical questions mailto:[email protected] Important Notices __________________________________________________________________________________________________________ (a) THIS DOCUMENT IS AN AUTHORIZED AND APPROVED PUBLICATION OF OSTA. THE SPECIFICATIONS CONTAINED HEREIN ARE THE EXCLUSIVE PROPERTY OF OSTA BUT MAY BE REFERRED TO AND UTILIZED BY THE GENERAL PUBLIC FOR ANY LEGITIMATE PURPOSE, PARTICULARLY IN THE DESIGN AND DEVELOPMENT OF WRITABLE OPTICAL SYSTEMS AND SUBSYSTEMS. THIS DOCUMENT MAY BE COPIED IN WHOLE OR IN PART PROVIDED THAT NO REVISIONS, ALTERATIONS, OR CHANGES OF ANY KIND ARE MADE TO THE MATERIALS CONTAINED HEREIN. 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THIS DOCUMENT DEFINES ONLY ONE APPROACH TO COMPATIBILITY, AND OTHER APPROACHES MAY BE AVAILABLE IN THE INDUSTRY. Universal Disk Format® and UDF® are registered marks of the Optical Storage Technology Association. i CONTENTS 1. INTRODUCTION......................................................................................................1 1.1 Document Layout .......................................................................................................................2 1.2 Compliance .................................................................................................................................3 1.3 General References.....................................................................................................................4 1.3.1 References ...............................................................................................................................4 1.3.2 Definitions ...............................................................................................................................4 1.3.3 Terms.......................................................................................................................................7 1.3.4 Acronyms ................................................................................................................................7 2. BASIC RESTRICTIONS & REQUIREMENTS....................................................8 2.1 Part 1 - General ........................................................................................................................11 2.1.1 Character Sets........................................................................................................................11 2.1.2 OSTA CS0 Charspec.............................................................................................................12 2.1.3 Dstrings .................................................................................................................................12 2.1.4 Timestamp .............................................................................................................................13 2.1.5 Entity Identifier .....................................................................................................................14 2.1.6 Descriptor Tag Serial Number at Formatting Time...............................................................19 2.1.7 Volume Recognition Sequence .............................................................................................19 2.2 Part 3 - Volume Structure .......................................................................................................20 2.2.1 Descriptor Tag.......................................................................................................................20 2.2.2 Primary Volume Descriptor...................................................................................................21 2.2.3 Anchor Volume Descriptor Pointer.......................................................................................23 2.2.4 Logical Volume Descriptor ...................................................................................................24 2.2.5 Unallocated Space Descriptor ...............................................................................................26 2.2.6 Logical Volume Integrity Descriptor.....................................................................................26 2.2.7 Implementation Use Volume Descriptor ...............................................................................29 2.2.8 Virtual Partition Map.............................................................................................................31 2.2.9 Sparable Partition Map ..........................................................................................................31 2.2.10 Metadata Partition Map ....................................................................................................32 2.2.11 Virtual Allocation Table ...................................................................................................34 2.2.12 Sparing Table....................................................................................................................36 2.2.13 Metadata Partition.............................................................................................................38 2.2.14 Partition Descriptor...........................................................................................................45 2.3 Part 4 - File Structure ..............................................................................................................47 2.3.1 Descriptor Tag.......................................................................................................................47 2.3.2 File Set Descriptor.................................................................................................................48 2.3.3 Partition Header Descriptor...................................................................................................50 2.3.4 File Identifier Descriptor .......................................................................................................51 2.3.5 ICB Tag .................................................................................................................................54 2.3.6 File Entry...............................................................................................................................56 2.3.7 Unallocated Space Entry .......................................................................................................58 2.3.8 Space Bitmap Descriptor .......................................................................................................59 2.3.9