If anyone wants to play in XML... https://svn.apache.org/repos/asf/httpd/site/trunk/content/doap.rdf
is quite out of date with respect to relevant specifications. I started https://wiki.apache.org/httpd/Compatibility to begin recording the RFC's our implementation intends to comply with, if you want the cheat-sheet. And then there is RFC7540 for our mod_http2/mod_proxy_http2 components.
