Appendix C. DocBook Versions

Table of Contents
C.1. DocBook V3.0
C.2. DocBook V3.1
C.3. DocBook V4.0
C.4. DocBook 5.0
C.5. DocBk XML

The OASIS DocBook Technical Committee (TC) is committed to the continued evolution of DocBook. As new needs are expressed by the DocBook-user community, the committee will adapt DocBook so it continues to meet the needs of its users.

The TC observes a very cautious policy regarding changes to the DTD. Backward-incompatible changes can only be introduced:

Changes made at point-releases are always backward-compatible to the previous major release. This policy assures that DocBook users always have time to prepare for any coming changes.

This appendix describes the changes planned for DocBook.

C.1. DocBook V3.0

> DocBook V3.0 was released in 1997. It has been widely adopted and integrated into several commercial products. It is likely that DocBook V3.0 will be in wide use for a while.

C.2. DocBook V3.1

DocBook V3.1, released in February 1999 introduced a number of new elements:


MediaObject is a wrapper around VideoObject, AudioObject, ImageObject, and TextObject. The purpose of MediaObject is twofold: first, it introduces new element types to include video and audio content; second, it provides the option of alternative representations, including text, for objects in a document. MediaObjects also allow Captions that may be longer than a simple title.

Parallel to MediaObject are InlineMediaObject, an inline version, and MediaObjectCO, a media object with Callouts.

For now, media objects and graphics exist together in version 5.0. Graphic and InlineGraphic will be removed from DocBook.


A figure wrapper without a title. This element was added largely for symmetry.


An end-of-the-book Colophon.


Section is a recursive section. It exists parallel to, and must be used as an alternative to, Sect1.


A set of questions and answers.


The Constant inline is for identifying constants. It has a Class attribute for identifying "limits" as a specific kind of constant.


Many authors have requested a tag for identifying variable names. Most often Literal (with or without a role) has been chosen as a compromise, but you can't question the utility of identifying variable names, so VarName was added.

A tag for identifying variable values does not seem as necessary. For immutable values, a specific tag other than Literal seems unnecessary, and Replaceable exists for values that are supposed to be filled in by the user.

C.3. DocBook V4.0

DocBook V4.0 will introduce a number of backward-incompatible changes.

The policy of the DocBook TC is that backward-incompatible changes can only be introduced in a full version release. They must also be described in comments in the DTD at least one full version earlier. In other words, all the planned version 4.0 incompatibilities were announced with version 3.0.

Backward-incompatible changes to DocBook that are planned for version 4.0:

C.4. DocBook 5.0

DocBook v5.0 will also introduce backward-incompatible changes.

These changes will be announced in version 4.0, although several were announced with version 3.1 as well.

Backward-incompatible changes to DocBook that are planned for version 4.0:

C.5. DocBk XML

The DocBk XML DTD is an XML version of DocBook produced by Norman Walsh. It is a faithful translation of DocBook, as described in Section B.2.

Although it has not been officially adopted by the DocBook Technical Committee, the TC does have concrete plans to produce an official XML version of DocBook in version 5.0. This is likely to be based on the DocBk XML DTD, or very closely resemble it.

The DocBk XML DTD is supplied on the CD-ROM. It is also available from > >

Copyright © 1999 O'Reilly & Associates, Inc. All rights reserved.