- DocBook. That is cool too, but it's XML and there's nothing to add about it.
Well, I will try to add something, though :).
XML is good as a standard for data exchange between different computer applications
(with incredible overhead, though), but it has absolutely inappropriate
syntax for manual editing by a human. In fact, it's as bad as naked HTML, despite
of all possible automated editing tools. The syntax does matter! In DocBook
you physically enclose sections into chapters, subsections into sections, and so on.
But look into any paper book they all have linear structure! You just read
the text and do not care much about its structure, in the meaning of
etc. Similarly, a writer wants just to mark
a certain line as a starting point of a new subsection, but never incapsulate
it into the enclosing section.
In DocBook you have extremely long elements, that are very hard for manual handling.
In general, it's a bad idea to enforce using solid elements longer than
a couple of screen pages. However, despite of all
disadvantages of XML, it might be the only appropriate solution when strict
structurization is a necessity, for example, when there's a whole department
working on documentation.
AGDoc can produce DocBook XML too, because it's all configurable.
In fact, when debugging the HTML config file for this site, I achieved
producing well formed XHTML, that can be easily read by any XML parser.
AGDoc can perfectly structurize the sources and produce
well formed DocBook format, with nested chapters, sections, subsections, etc.
The task of automatic syntax highlighting can be probably solved, but
it definitely requires some efforts.