Literate Programming
Always have to quote Knuth (1984):
Let us change our traditional attitude to the construction of programming: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do
NormanWalsh has written and presented a paper on using literate programming using DocBook (Walsh, 2003). His paper, a copy of which is on-line, gives some further references. His DocBook literate programming tool (really just a collection of XSL stylesheets, which is all you need to process literate programs written in XML) is available on the DocBook open repository on SourceForge.
References
Knuth, Donald E. (1984). "Literate Programming," The Computer Journal, 27(2), pp 97-111, May.
Walsh, Norman (2002). "Literate Programming in XML". Proceedings of XML 2002, December.