The DocBook Document Type

Committee Specification 4.2, 16 July 2002

Document identifier:

cs-docbook-docbook-4.2 (XML, HTML, PDF)



Norman Walsh, Sun Microsystems, Inc. <Norman.Walsh@Sun.COM>


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 4.2 release is a maintainance release. It introduces no backwards-incompatible changes.


This Committee Specification was approved for publication by the OASIS DocBook Technical Committee. It represents the consensus of the committee.

Please send comments on this specification to the <> list. To subscribe, send an email message to <> with the word "subscribe" as the body of the message.

The errata page for this specification is at

Table of Contents

1. Introduction
2. Terminology
3. The DocBook Document Type V4.2
3.1. Changes in DocBook V4.2
3.2. Changes in DocBook V4.2CR3
3.3. Changes in DocBook V4.2CR2
3.4. Changes in DocBook V4.2CR1
4. Release Notes
4.1. Relationship to the QIC Technical Committee
4.2. Relationship to the Dublin Core
5. Changes Proposed for DocBook V5.0
6. Changes Proposed for DocBook V6.0


A. OASIS DocBook Technical Committee (Non-Normative)
B. Notices
C. Intellectual Property Rights
D. 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 4.2 release is a maintainance release. It introduces no backwards-incompatible changes. All valid DocBook 4.1 documents are also valid DocBook 4.2 documents.

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 Committee Specification 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 V4.2

The DocBook document type is distributed for XML and SGML from the DocBook site at OASIS

3.1. Changes in DocBook V4.2

There are no backwards-incompatible changes in this release.

Each of the changes made between DocBook V4.2CR3 and DocBook V4.2 is summarized here.

The appellation "CR3" was removed from comments, public, and system identifiers.

3.2. Changes in DocBook V4.2CR3

There are no backwards-incompatible changes in this release.

Each of the changes made between DocBook V4.2CR2 and DocBook V4.2CR3 is summarized here.

The only changes made for the CR3 release were in comments in the various modules. The previous release, labelled "Candidate Release 2", erroneously contained the CR1 files. This release fixes that error.

3.3. Changes in DocBook V4.2CR2

There are no backwards-incompatible changes in this release.

Each of the changes made between DocBook V4.2CR1 and DocBook V4.2CR2 is summarized here.

3.3.1. Bug Fixes

  • The; reference was added to %info.class;. Its absence was an oversight, it should always have been there.

  • The SVG notation was added to %notation.class;. Its absence was an oversight, it should always have been there.

  • Changed the mechanism for identifying incorrectly configured DocBook customization layers. In DocBook V4.2CR1, if a customization layer incorrectly enabled both %sgml.features; and %xml.features;, the DTD was syntactically invalid. This caused problems for certain kinds of DTD parsing tools that ignore marked sections.

    Instead of producing a syntax error, the new mechanism simply points all of the DTD modules to a file that contains no declarations. The content of this file,, explains the cause of the error.

3.4. Changes in DocBook V4.2CR1

Each of the changes made between DocBook V4.1 and DocBook XML V4.1.2 is summarized here. For complete details, consult the individual RFEs and the meeting minutes.

3.4.1. Bug Fixes

  • RFE 434439: Add language attribute to MethodSynopsis

  • RFE 435485: Parameter entity %tbl.table.mdl; can't be redefined cleanly

  • Expand the content model of the following elements from %smallcptr.char.mix; back to %cptr.char.mix;: interfacename, action, database, filename, hardware, keycap, option, parameter, property, and systemitem (command, interface, and literal were never reduced).

3.4.2. Enhancements

  • RFE 417671: Add recursive section element to Refentry

  • RFE 426382: Allow SimpleSect inside Section

  • RFE 431413: Former RFE 121: Add markup for signals

  • RFE 431415: Former RFE 124: Add markup for host identifiers

  • RFE 431418: Former RFE 128: Typing and linking in FuncDef (partially implemented)

  • RFE 431419: Former RFE 130: Markup protocol, Filesystem type, and partion.

  • RFE 435466: %beginpage.exclusion; not used in dbpool.mod

  • RFE 436072: Need parameter entity for info* content

  • RFE 439136: Allow literallayout in epigraph

  • RFE 440597: Add SVG notation

  • RFE 440667: Add class attribute to orgname. This proposal deprecates corpname as proposed.

  • RFE 470599: Revise graphic attributes as proposed.

  • RFE 480956: Add co to userinput, etc.

  • RFE 480957: New name and address markup as proposed.

  • Former RFE 133: Added newsgroup class to systemitem.

  • Former RFE 140: Allow multiple msgexplan inside simplemsgentry.

  • RFE 482053: Former RFE 119: Add support for DOI in meta.

  • RFE 480955: Add coref.

  • RFE 482817: An errortext element will be added. The processing expectations of errorname will be clarified. See also RFE 482922.

  • RFE 482820: An extension value will be added to the class attribute of filename.

  • RFE 482821: Add introductory material to the beginning of list elements.

  • RFE 487482: Add metadata (blockinfo) to block elements: equation, example, figure, informalequation, informalexample, informalfigure, informaltable, itemizedlist, legalnotice, msgset, orderedlist, procedure, qandadiv, qandaentry, qandaset, table, and variablelist.

  • RFE 491629: Allow personname in inline content as proposed.

  • RFE 492099: Add new attributes to olink.

  • RFE 498848: Allow segmentedlists with only a single seg.

  • RFE 501363: Add %section.class; parameter entity.

  • RFE 513426: Add text alternative for tables as proposed.

  • Extended metadata elements to capture all of the Dublin Core Metadata Element Set, Version 1.0.

4. Release Notes

4.1. Relationship to the QIC Technical Committee

DocBook and the Customer Information Quality (QIC) TC both define markup for names and addresses. In general, the requirements for bibliographic name metadata in DocBook are far less complex than the requirements for maintaining customer information.

DocBook name and address markup is a proper subset of the QIC xNL markup with the following simple transformation:

DocBook ElementQIC xNL Element

4.2. Relationship to the Dublin Core

DocBook Version 4.2 defines a proper superset of the Dublin Core Metadata Element Set, Version 1.0. In previous versions of DocBook, there were several Dublin Core elements that were not easily derived from DocBook metadata.

The following table summarizes the Dublin Core mapping for DocBook (as amended).

DC ElementDC LabelDocBook Element(s)
Author or CreatorCreatorauthor, editor, othercredit
Subject and KeywordsSubjectkeywordset, subjectset
PublisherPublisherpublisher, publishername
ContributorContributorauthor, editor, othercredit, collab
DateDatedate, pubdate
TypeTypeDerived from document element and status attribute
Resource IdentifierIdentifierbiblioid
LanguageLanguagelang or xml:lang attribute
Rights ManagementRightscopyright, legalnotice

In some cases, additional role attributes or other logic may be required to determine the best mapping.

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. OASIS DocBook Technical Committee (Non-Normative)

The following individuals were members of the committee during the formulation of this Committee Specification:

  • Dennis Evans

  • Patricia Gee-Best

  • Paul Grosso

  • Dick Hamilton

  • Nancy (Paisner) Harrison

  • Sabine Ocker

  • Michael Sabrio

  • Michael Smith

  • Tim Teebken (prospective)

  • Norman Walsh (Chair, Editor)

B. Notices

Copyright © The Organization for the Advancement of Structured Information Standards [OASIS] 2001, 2002. 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.

C. 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 (

D. Revision History

Revision Committee Specification16 Jul 2002
Revision Candidate Release 328 May 2002
Revision Candidate Release 221 May 2002
Revision Candidate Release 119 Mar 2002
Revision Working Draft “Beta 1”20 Nov 2001



[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, and Eve Maler, editors. Extensible Markup Language (XML) 1.0 Second Edition. World Wide Web Consortium, 2000.

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