DITA can be used in the process of creating user assistance, and especially of Help systems, but is not currently (and may never be) used as a delivery format for user assistance itself.
DITA is a storage and authoring format, not a delivery format; it is a presentation-neutral format. The separation of content and form is fundamental to DITA's design; content is written in DITA and must be transformed to a reading format before it can be delivered to the reader.
In principle, content written in DITA can be transformed to any reading format. In practice, it's not that simple. Before DITA can be transformed, a transformation process has to be devised. Many DITA authoring and publishing tools come with standard transformers for most common delivery formats, such as PDF, RTF and HTML. The DITA Open Toolkit, an open source collection of utilities and documentation to help writers work with DITA, includes basic transformers for PDF, RTF, HTML, DocBook™, Eclipse Help, and Microsoft HTML Help.
User assistance content is not defined by its format. A document in Microsoft HTML Help format isn't necessarily a Help system; user assistance is defined by the nature of the content. Conversely, user assistance content doesn't have to be delivered in a traditional Help format.
DITA promotes a single-source approach to documentation, so user assistance may commonly be one of a number of deliverables produced from a repository of information topics. The process of producing simple Help systems from DITA content using the standard DITA Open Toolkit transforms is straight-forward. It is a little more complicated to deliver such DITA-generated content for context-sensitive Help, but still readily achievable. Likewise, in principle, it is a trivial matter to incorporate DITA content into embedded user assistance and user interface elements using standard XML™ tools and techniques. There is not yet a standard approach to user assistance, so there is also no standard way of using DITA in this way. Different organizations tend to develop their own individual, custom approaches, using in-house technical expertise to do so.
Moving beyond simple Help systems, however, is currently difficult, but not impossible. The DITA Technical Committee is developing some enhancements to the DITA standard to allow these processes to be simplified. However, the apparent simplicity or complexity of using DITA for Help authoring will be in future determined by the capabilities of DITA editing and publishing tools. When it comes down to it, DITA is just a standard and good tools are needed to work with good standards.
Tony Self
HyperWrite Pty. Ltd.
Chairperson, OASIS DITA Help Subcommittee