From Republicorp International:
XDK is the latest technology for creating professional Help systems and online manuals. It uses XML technology to create and manage Help projects from 100 to 100,000 topics. XDK is Help systems will run on any browser and on any platform, providing your users with a hierarchical table of contents, full text searching, indexing, graphics, tab bars, glossaries XDK lets you use Word as your editing environment, so you have access to all of its powerful formatting, design, and grammar tools. XDK is also the tool to give you output to all the popular help formats, plus the new XmheLp Web based help system. You can even automatically convert standard Word documents (complete with embedded Office objects) into Help, HTML, or XHTML. XDK gives you access to the broadest range of online technologies for context-sensitive Help systems, online manuals, and Web based systems.