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.
This appendix describes the changes planned for DocBook.
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.
An end-of-the-book Colophon.
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 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 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.
Comment will be renamed to Remark and will be excluded from itself.
The Subject attribute on GlossDef will be renamed Keyword.
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).
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.