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DITA is one of the most important innovations in XML publishing in recent memory. And if you're using or plan to use XML for publishing technical documentation, you will encounter DITA sooner or later.
Short for "Darwin Information Typing Architecture," DITA is an IBM invention that the company contributed to the community under the auspices of OASIS, the Organization for the Advancement of Structured Information Standards.
This document is not intended to be a "how to" guide for implementers, nor is it deeply technical. IBM has published a great deal of excellent, in-depth technical information online.
This author gratefully acknowledges the people and resources of IBM for his understanding of DITA, but he remains solely responsible for any errors, omissions or misinterpretations.
Why You Should Care About DITA
As with XML itself, DITA embodies a few simple constructs that have profound implications. Defining DITA is relatively easy; the hard part is describing its implications. So we'll begin with the definition.
DITA is an architecture based on XML for publishing technical information. In some ways, it's like DocBook, which was created some years ago as the basis for XML-based publishing of technical manuals, in particular for computer hardware and software documentation. (In researching this article, we came across an interesting set of resources. Among several worthwhile white papers, they have a white paper on DITA that's more technical than this series and a little dated, but it includes a worthwhile comparison against DocBook.)
But there are two aspects of DITA that make it special:
- Modular ? DITA defines a Topic DTD that supports a modular approach to creating information. A topic is an information component, not a complete book. A topic covers one aspect of a specific area of interest. (For example, this article could be divided into three topics: introduction, overview, and origins.) DITA defines a mechanism for combining topics into documents so that the documents contain a hierarchy that is appropriate for the document. For example, the hierarchy of a book usually consists of chapters, sections and sub-sections.
- Adaptable ? The Topic DTD is similar to HTML in that it specifies a set of generic elements each with different formatting such as titles, paragraphs and lists. To adapt the Topic DTD to your specific needs, DITA defines a mechanism called "specialization" that allows you to define new tags that inherit their behavior and properties from tags in Topic. Specialization allows downstream applications that are DITA-aware to handle an unknown tag by treating it as the tag from which it inherits its properties. For example, you could create a tag called "Procedure" that inherits from "Ordered List" and a tag called "Step" that inherits from "List Item." Although you may want to add specific processing for Procedure and Step to your application, a DITA-aware application that knows nothing about these tags would handle Procedure and Step as if they were Ordered List and List Item instead. For instance, a DITA-aware publishing application that knows nothing about Step would format it as if it were a List Item.
Knowing the definition of DITA does not give you enough background for understanding its implications. So now let's start the story.
Let's begin by re-visiting some of the key objectives of an XML publishing system:
- Reuse ? To eliminate redundancy, improve accuracy, and reduce the effort to update information, XML helps you reuse and repurpose information so that you can create a single source of information in which a single change in the source will automatically update all of the documents where that information appears.
- Sharing ? XML lets you construct your information in a way that allows other groups both within and outside your organization to incorporate your information automatically into their own processes, adding further value to the information you create. - Relevance ? You can use XML to help you create your information in modules that you automatically assemble according to the needs of each individual so that he gets everything he needs and only what he needs.
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