The DocBook Document Type

Working Draft 4.4b2, 26 Aug 2004

Document identifier:

wd-docbook-docbook-4.4b2 (XML, HTML, PDF)



Norman Walsh, Sun Microsystems, Inc. 


DocBook is general purpose [XML] and [SGML] document type particularly well suited to books and papers about computer hardware and software (though it is by no means limited to these applications).

The Version 4.4b2 release is a maintenance release. It introduces no backwards-incompatible changes.


This Working Draft is an editor's draft. It does not necessarily represent the consensus of the committee.

Please send comments on this specification to the list. To subscribe, please use the OASIS Subscription Manager.

The errata page for this specification is at

Table of Contents

1. Introduction
2. Terminology
3. The DocBook Document Type V4.4b2
3.1. Changes in DocBook V4.4b2
3.2. Changes in DocBook V4.4b1
4. Release Notes
5. Changes Proposed for DocBook V5.0
6. Changes Proposed for DocBook V6.0


A. The DocBook Media Type
1. Registration of MIME media type application/docbook+xml
2. Fragment Identifiers
B. OASIS DocBook Technical Committee (Non-Normative)
C. Notices
D. Intellectual Property Rights
E. Revision History

1. Introduction

DocBook is general purpose XML and SGML document type particularly well suited to books and papers about computer hardware and software (though it is by no means limited to these applications).

The DocBook Technical Committee maintains the DocBook schema. DocBook is officially available as a Document Type Definition (DTD) for both XML and SGML. It is unofficially available in other forms as well.

The Version 4.4b2 release is a maintainance release. It introduces no backwards-incompatible changes. All valid DocBook 4.3 documents are also valid DocBook 4.4b2 documents.

The genesis of this release is a bug in the catalog files for DocBook V4.3. The Committee decided to produce a 4.4 release, incorporating a few recent backwards-compatible changes, rather than simply produce a 4.3.1 release to fix the bugs.

The DocBook Technical Committee welcomes bug reports and requests for enhancement (RFEs) from the user community. The current list of outstanding requests is available through the SourceForge tracker interface. This is also the preferred mechanism for submitting new requests. Old RFEs, from a previous legacy tracking system, are archived for reference.

2. Terminology

The key words must, must not, required, shall, shall not, should, should not, recommended, may, and optional in this Working Draft are to be interpreted as described in [RFC 2119]. Note that for reasons of style, these words are not capitalized in this document.

3. The DocBook Document Type V4.4b2

The DocBook document type is distributed for XML and SGML from the DocBook site at OASIS. DocBook is also available from the mirror on

3.1. Changes in DocBook V4.4b2

There are no backwards-incompatible changes in this release.

Each of the changes made between DocBook V4.4b1 and DocBook V4.4b2 is summarized here. For complete details, consult the individual RFEs and the meeting minutes.

3.1.1. Bug Fixes

  • Version 4.4b2 includes the W3C XML Entity Declarations for Characters. These entities are distributed for historical compatibility and user convenience. The DocBook Technical Committee no longer attempts to maintain these definitions and will periodically update them from the W3C site if and as they are updated there.

  • Removed xml:base from the SGML DTD.

  • Allow HTML tables to nest (allow table and informaltable inside td and th).

  • Changed the rules attribute, which can appear on HTML tables, from an enumeration to CDATA. This avoids a conflict with the enumerated values on the frame attribute on CALS tables.

3.1.2. Enhancements

  • Added bibliolist.

  • Added a parameter entity to allow customizers to exclude the € character entity.

3.2. Changes in DocBook V4.4b1

There are no backwards-incompatible changes in this release.

Each of the changes made between DocBook V4.3 and DocBook V4.4b1 is summarized here. For complete details, consult the individual RFEs and the meeting minutes.

3.2.1. Bug Fixes

  • Added the HTML Table Module to the catalog files for DocBook and DocBook XML.

3.2.2. Enhancements

  • Added package element per the Febuary, 2004 meeting.

  • Allow imageobjectco as a child of mediaobject (this effectively makes mediaobjectco unnecessary) per the Febuary, 2004 meeting.

  • Added biblioref element per the May, 2004 meeting.

  • Added spacing attribute to variablelist per the April, 2004 meeting.

  • Added superscript and subscript to the content model of the gui* elements per the May, 2004 meeting.

4. Release Notes

XML validation technologies have evolved rapidly in the last few years. The Technical Committee is exploring the possibility of using RELAX NG as the principal validation technology for DocBook V5.0. The move to RELAX NG will also cause some one time backward-incompatible changes which are not listed in this specifcation.

5. Changes Proposed for DocBook V5.0

The following backwards-incompatible changes were announced in DocBook V4.0, the DocBook Technical Committee expects to incorporate them into DocBook V5.0.

Each of the changes proposed is summarized here. For complete details, consult the individual RFEs and the meeting minutes.

  • DocBook V5.0 will be primarily an XML DTD. This will require a wide range of changes. As a result, DocBook V5.0 will more closely resemble The XML version of DocBook V4.x than the SGML version.

  • Planned parameter entity reorganization may reduce some content models. The goal of this effort is to remove a large number of spurious elements that snuck into content models during the first parameter entity reorganization (circa DocBook 2.4). In practice the TC expects changes to have very little "real world" impact.

  • The coords attribute will be removed from areaset.

  • The articleinfo element will be removed from biblioentry.

  • The contents attribute will be removed from bookinfo and setinfo.

  • The %indexdivcomponent.mix; parameter entity will be restricted. Numbered figures and other elements inappropriate for an index or setindex will be removed.

  • The revhistory element will be removed from glossterm.

  • RFE 416415: The constant class will be removed from systemitem.

  • The graphic and inlinegraphic elements will be removed.

  • Tables will be restricted from full CALS Table Model to the OASIS Exchange model.

6. Changes Proposed for DocBook V6.0

The DocBook Technical Committee expects to announce the following backwards-incompatible changes in DocBook V5.0, for eventual incorporation into DocBook V6.0.

Each of the changes proposed is summarized here. For complete details, consult the individual RFEs and the meeting minutes.

  • RFE 412476: The class attribute on productname will be #IMPLIED.

  • RFE 482810: The content model of msgtext is far too broad. It will be reduced to the same mixture as %example.mix;.

  • RFE 482811: The title element will be removed from %bibliocomponent.mix; (use citetitle instead).

  • RFE 482812: The content model of citetitle will be reduced from %para.char.mix; to %title.char.mix;.

  • RFE 482815: The synopsis element will be removed from %para.char.mix;.

  • RFE 482818: Simplify the content model of toc.

  • RFE 482819: The content models of the bibliography elements will be adjusted so that it is not possible to mix biblioset and bibliomset elements.

  • RFE 482922: The msgtext element will be constrained to occur only inside msgset. See also RFE 482817.

  • RFE 531851: Remove inline person name elements as proposed.

  • RFE 531855: Remove corpname as proposed.

A. The DocBook Media Type

This appendix registers a new MIME media type, "application/docbook+xml".

1. Registration of MIME media type application/docbook+xml

MIME media type name:


MIME subtype name:


Required parameters:


Optional parameters:

This parameter has identical semantics to the charset parameter of the application/xml media type as specified in [RFC 3023] or its successors.

Encoding considerations:

By virtue of DocBook XML content being XML, it has the same considerations when sent as "application/docbook+xml" as does XML. See [RFC 3023], Section 3.2.

Security considerations:

Several DocBook elements may refer to arbitrary URIs. In this case, the security issues of RFC 2396, section 7, should be considered.

Interoperability considerations:


Published specification:

This media type registration is for DocBook documents as described by [DocBook: TDG].

Applications which use this media type:

There is no experimental, vendor specific, or personal tree predecessor to "application/docbook+xml", reflecting the fact that no applications currently recognize it. This new type is being registered in order to allow for the deployment of DocBook on the World Wide Web, as a first class XML application.

Additional information:
Magic number(s):

There is no single initial octet sequence that is always present in DocBook documents.

File extension(s):

DocBook documents are most often identified with the extension ".xml".

Macintosh File Type Code(s):


Person & email address to contact for further information:

Norman Walsh, .

Intended usage:


Author/Change controller:

The DocBook specification is a work product of the DocBook Technical Committee at OASIS.

2. Fragment Identifiers

For documents labeled as "application/docbook+xml", the fragment identifier notation is exactly that for "application/xml", as specified in [RFC 3023] or its successors.

B. OASIS DocBook Technical Committee (Non-Normative)

The following individuals were members of the committee during the formulation of this Working Draft:

  • Jeff Beal

  • Steve Cogorno

  • Adam Di Carlo

  • Paul Grosso

  • Dick Hamilton

  • Nancy Harrison

  • Scott Hudson

  • Mark Johnson

  • Jirka Kosek (prospective)

  • Larry Rowland

  • Michael Smith

  • Robert Stayton, Secretary

  • Norman Walsh, Chair, Editor

C. Notices

Copyright © The Organization for the Advancement of Structured Information Standards [OASIS] 2001, 2002, 2003, 2004. All Rights Reserved.

OASIS takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on OASIS's procedures with respect to rights in OASIS specifications can be found at the OASIS website. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification, can be obtained from the OASIS Executive Director.

OASIS invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to implement this specification. Please address the information to the OASIS Executive Director.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to OASIS, except as needed for the purpose of developing OASIS specifications, in which case the procedures for copyrights defined in the OASIS Intellectual Property Rights document must be followed, or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by OASIS or its successors or assigns.


OASIS has been notified of intellectual property rights claimed in regard to some or all of the contents of this specification. For more information consult the online list of claimed rights.

D. Intellectual Property Rights

For information on wether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the DocBook web page (

E. Revision History

Revision Working Draft “Beta 2” 26 Aug 2004
Revision Working Draft “Beta 1” 09 Jun 2004



[SGML] JTC 1, SC 34. ISO 8879:1986 Information processing -- Text and office systems -- Standard Generalized Markup Language (SGML). 1986.

[XML] Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, et. al., editors. Extensible Markup Language (XML) 1.0 (Third Edition). World Wide Web Consortium, 04 Feb 2004.

[RFC 2119] IETF (Internet Engineering Task Force). RFC 2119: Key words for use in RFCs to Indicate Requirement Levels. S. Bradner. 1997.

[RFC 3023] IETF (Internet Engineering Task Force). RFC 3023: XML Media Types. M. Murata, S. St. Laurent, D. Kohn. 2001.

[DocBook: TDG] Norman Walsh and Leonard Meullner. DocBook: The Definitive Guide. O’Reilly & Associates, 1999.