Yodl is a package that implements a pre-document language and tools to
process it.  The idea of Yodl is that you write up a document in a
pre-language, then use the tools (e.g.  yodl2html) to convert it to
some final document language.  Current converters are for HTML, ms,
man, LaTeX SGML and texinfo, plus a poor-man's text converter.  Main
document types are "article", "report", "book" and "manpage".  The
Yodl document language is designed to be easy to use and extensible.