I remember attending one of the first presentations about DITA sometime around 2001 by Michael Priestley at a Toronto STC meeting and have followed its development with interest since, although I don’t use it. I knew its genesis was from IBM’s GML and BookMaster but not much more than that. However, Elliot Kimber (aka Dr. Macro) has written a fascinating article explaining the early genesis of both DITA and DocBook, the other major competing XML-based documentation architecture.
Soon after this Wayne and I, along with Don Day, Simcha Gralla, and others, started working on IBM’s SGML replacement for the GML-based BookMaster language, which was used for most of IBM’s documentation and had more than 600 element types, reflecting a very broad range of requirements. BookMaster allowed for very efficient creation of documentation delivered in print and online on 5 different computer platforms using IBM’s BookManager tool, which provided electronic books starting in the mid 80’s. But BookMaster was also big and difficult to change or extend. It suffered the same problems that all large all-encompassing vocabularies suffer: it became a tarball that was difficult to adapt to new requirements. IBM had a committee that considered BookMaster change requests and it worked on a 6-month cycle at best. BookMaster was also based on proprietary IBM composition technology, the Document Composition Facility, which was becoming obsolete with the development of PCs and more modern processing languages and systems.
The comments about BookMaster were particularly interesting. I worked at IBM for a while in the early 90s and had to learn BookMaster – on a 3279 terminal, no less. It was hard, but learning GML gave me a big leg up in learning HTML – I picked up the basics in an afternoon.