Skip to main content
Version: DocBook V4.5

Appendix C. DocBook Versions

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:

  • In major releases (4.0, 5.0, 6.0, and so on)

  • Only if the change was described in comments in the DTD in the previous major release

This appendix describes the changes planned for DocBook.

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.

DocBook V4.1 and DocBook XML V4.1.2

DocBook V4.1 and DocBook XML V4.1.2 became an OASIS Standard in February 2001.

DocBook V4 introduced 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:

  • The DocInfo element will be split out into ChapterInfo, AppendixInfo, and so on. ArtHeader will be renamed to ArticleInfo. SeriesInfo may be discarded because it has become a special case of BiblioSet. BookBiblio will be discarded in favor of a new, more inclusive, structure for BookInfo (and for ArticleInfo, whose earlier ArtHeader form contained BookBiblio).

  • The %article.class; entity may be removed from the Book content model, and made part of a new top-level document hierarchy.

  • The %nav.class; entity, which appears in several divisions, will allow ToCchap instead of ToC.

  • MsgText will be moved from %tech.char.class; to a more appropriate parameter entity.

  • The following elements will have their content constrained to the %smallcptr.char.mix; mixture: Action, Command, Database, Filename, Hardware, Interface, KeyCap, Literal, Option, Parameter, Property, and SystemItem.

  • AuthorBlurb and Affiliation will be removed from %person.ident.mix; and a new wrapper element will be created to allow association of those two elements with Author name information.

  • Epigraph will not be appearing in BlockQuote.

  • Comment will be renamed to Remark and will be excluded from itself.

  • GlossTerm will be excluded from itself, and may be split into an element that appears in a Glossary and an element that can appear in the main text.

  • The Subject attribute on GlossDef will be renamed Keyword.

  • Two SegTitle elements will be required in SegmentedList.

  • Graphic and InlineGraphic will be declared EMPTY. This change will require that end tags be removed and that any embedded graphic content be stored outside the SGML source and pointed to from an Entityref or Fileref attribute.

  • The OptMult and ReqMult values for the Choice attribute on Group will be removed. Use the Rep attribute instead to indicate that the choice is repeatable.

  • The content model group inside FuncSynopsis starting with FuncDef will not be available; you will have to use FuncPrototype. Also, you will be able to have a mixture of FuncPrototypes and FuncSynopsisInfos (this is not backward-incompatible all by itself).

  • The EnvironVar and Prompt values for the Class attribute on SystemItem will be eliminated; use the EnVar and Prompt elements instead.

DocBook V4.2

DocBook V4.2 fixed a couple of small bugs and introduced a number of new features. Changes in DocBook V4.2 are explained in the DocBook Document Type Version 4.2.

EBNF Module

FIXME: write this section

HTML Forms Module

FIXME: write this section

MathML Module

FIXME: write this section

SVG Module

FIXME: write this section