Best working file format for writing open source books?
makecheck: I have used reStructuredText (which both "docutils" and "prest" can use to generate documents).  The source text actually is the plain text "output", while it is still possible to automatically generate HTML, etc.For something as complex as a book, reStructuredText is best; though I often fall back on the simple Textile format for really short documents that still need to be converted to HTML.