This chapter provides an overview of DocBook, starting with its history. It includes a description of DocBook V5.0 and the changes from DocBook V4.x to V5.0.
DocBook is more than 15 years old. It began in 1991 as a joint project of HaL Computer Systems and O’Reilly & Associates (as O’Reilly Media, Inc. was then called). Its popularity grew, and eventually it spawned its own maintenance organization, the Davenport Group. In mid-1998, maintenance moved to a Technical Committee of the Organization for the Advancement of Structured Information Standards (OASIS).
DocBook’s roots are in SGML, where it was defined with a Document Type Definition, or DTD. DocBook was released as both an SGML and an XML vocabulary starting with V4.1. The V4.x versions of DocBook, like the versions that came before them, were also defined with a DTD. Starting with DocBook V5.0, DocBook is exclusively an XML vocabulary defined with RELAX NG and Schematron.
The DocBook DTD was originally designed and implemented by HaL Computer Systems and O’Reilly & Associates around 1991. It was developed primarily to facilitate the exchange of UNIX documentation originally marked up in troff. Its design appears to have been based partly on input from SGML interchange projects conducted by the Unix International and Open Software Foundation consortia.
When DocBook V1.1 was published, discussion about its revision and maintenance began in earnest in the Davenport Group, a forum created by O’Reilly for computer documentation producers. DocBook V1.2 was influenced strongly by Novell and Digital.
In 1994, the Davenport Group became an officially chartered entity responsible for DocBook’s maintenance. DocBook V1.2.2 was published simultaneously. The founding sponsors of this incarnation of Davenport include the following people with their affiliations at that time:
- Jon Bosak, Novell
- Dale Dougherty, O’Reilly & Associates
- Ralph Ferris, Fujitsu OSSI
- Dave Hollander, Hewlett-Packard
- Eve Maler, Digital Equipment Corporation
- Murray Maloney, SCO
- Conleth O’Connell, HaL Computer Systems
- Nancy Paisner, Hitachi Computer Products
- Mike Rogers, SunSoft
- Jean Tappan, Unisys
Under the auspices of the Davenport Group, the DocBook DTD began to widen its scope. It was now being used by a much wider audience and for new purposes such as direct authoring with SGML-aware tools and publishing directly to paper. As the largest users of DocBook, Novell and Sun had a heavy influence on its design.
In order to help users manage change, the new Davenport charter established the following rules for DocBook releases:
Minor versions (“point releases” such as V2.2) could add to the markup model, but could not change it in a backward-incompatible way. For example, a new kind of list element could be added, but it would not be acceptable for the existing itemized list model to start requiring two list items inside it instead of only one. Thus, any document conforming to version
n.0 would also conform ton.m.Major versions (such as V3.0) could both add to the markup model and make backward-incompatible changes. However, the changes would have to be announced in the last major release.
In 2009, the Technical Committee updated this policy to allow backward-incompatible changes in a major version, provided the change is announced in a major or minor release at least six months in advance.
Major version introductions must be separated by at least a year.
V3.0 was released in January 1997. DocBook’s audience continued to grow, but many of the Davenport Group stalwarts became involved in the XML effort, and development slowed dramatically. The idea of creating an official XML-compliant version of DocBook was discussed, but not implemented at that time.
In July 1998, the sponsors moved the standards activities from the Davenport Group to OASIS, forming the OASIS DocBook Technical Committee with Eduardo Gutentag of Sun Microsystems as chair.
The OASIS DocBook Technical Committee is continuing the work started by the Davenport Group. The transition from Davenport to OASIS was very smooth, in part because the core team remained essentially the same.
DocBook V3.1, published in February 1999, was the first OASIS release. It integrated a number of changes that had been “in the wings” for some time. In March 2000, Norm Walsh became chair of the Technical Committee.
In February 2001, OASIS made DocBook SGML V4.1 and DocBook XML V4.1.2 official OASIS Specifications.
In October 2005, the DocBook Technical Committee released the first beta test version of DocBook V5.0. Development of the DocBook 4.x series continued in parallel with the development of V5.0. In October 2006, the DocBook Technical Committee released DocBook V4.5, the last release planned in the 4.x series.
In 2008, the Publisher’s Subcommittee was chartered to develop and maintain official variants of DocBook in support of the publishing industry. The subcommittee focuses on schema customizations to support: periodicals as regularly published technical notes or journals, book publishing (such as business, legal, medical, and other nontechnical domains), educational textbooks, and other document types as appropriate for this industry.
DocBook V5.0 became an official Committee Specification in June 2009 and became an official OASIS Standard in October 2009. The Technical Committee continues DocBook development to ensure that the schema will continue to meet the needs of its users.
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