restructuredtext?
RestructuredText is very powerful, and has an official specification. Basically what Markdown is missing. Yet, it is plain text and easy to parse.
foo
======================
... the easy and built-in extensibility is a huge plus though, as is Sphinx and the pretty good output writers for many formats. Sphinx btw. works with Markdown, too.Quite possibly my biggest annoyance with rST/Sphinx is the hanging toctree issue, and poor support for multi-format images/figures.
The 100 % offline search in Sphinx is somewhat of a mixed bag and doesn't always give good results, though it's fine for reference works.