The Annex language is a markup language for protocols. Its current (only) feature is to create protocol descriptions that can be used in LaTeX documents.
Annex is based on YAML. As of now, there is no further description of the language except for the example files which make use of most language features.
To convert a file from Annex to TeX, just run
annex-convert infile.yml outfile.tex
If you use a chart generated with Annex in your publication, please include a notice (e.g., "Chart generated with Annex.") somewhere.