@0x4d6165 that's just tip of iceberg, so here's the specs i'm more or less tryna implmenet, atom in particular is designed to fit any xml into... oh shit forgot media sitemap
DC - www.dublincore.org/specifications/dublin-core/dcmi-terms/#section-7
foaf - friend of friend, for user profiles mostiy xmlns.com/foaf/spec/
maze+xml - for web nav mamund.com/media-types/index.html
mods - library of congress metadata schema www.loc.gov/standards/mods/userguide/userguide-index.html
nws - the national weather service has an xml graphical.weather.gov/xml/
opg - opengraph, facebook link embed ogp.me
osm - open street map wiki.openstreetmap.org/wiki/OSM_XML/XSD
owl -it's a whole thing www.w3.org/TR/2012/REC-owl2-overview-20121211/#ref-owl-2-specification
recipeml - recipes www.formatdata.com/recipeml/
schema - basically seo slop schema.org/docs/full.html
xbel - bookmarks pyxml.sourceforge.net/topics/xbel/docs/html/xbel.html
xcal -calandars / events datatracker.ietf.org/doc/html/rfc6321
xcard -contacts datatracker.ietf.org/doc/html/rfc6351#section-3
xmltv - for tv schedules github.com/XMLTV/xmltv github.com/XMLTV/xmltv/blob/master/xmltv.dtd
xspf -playlists www.xspf.org/spec
there's a few more I know I'm forgetting