Edit: /usr/share/mime/XMLnamespaces (1896B)
http://schema.omg.org/spec/XMI/2.0 XMI text/x-xmi
http://schema.omg.org/spec/XMI/2.1 XMI text/x-xmi
http://www.abisource.com/awml.dtd abiword application/x-abiword
http://www.apple.com/DTDs/PropertyList-1.0.dtd plist application/x-apple-systemprofiler+xml
http://www.daa.com.au/~james/dia-shape-ns shape application/x-dia-shape
http://www.gribuser.ru/xml/fictionbook/2.0 FictionBook application/x-fictionbook+xml
http://www.lysator.liu.se/~alla/dia/ diagram application/x-dia-diagram
http://www.metalinker.org/ metalink application/metalink+xml
http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul window application/vnd.mozilla.xul+xml
http://www.opengis.net/gml/3.2 gml application/gml+xml
http://www.opengis.net/kml/2.2 kml application/vnd.google-earth.kml+xml
http://www.topografix.com/GPX/1/0 gpx application/gpx+xml
http://www.topografix.com/GPX/1/1 gpx application/gpx+xml
http://www.w3.org/1998/Math/MathML math application/mathml+xml
http://www.w3.org/1999/02/22-rdf-syntax-ns# RDF application/rdf+xml
http://www.w3.org/1999/XSL/Format root text/x-xslfo
http://www.w3.org/1999/XSL/Transform stylesheet application/xslt+xml
http://www.w3.org/1999/xhtml html application/xhtml+xml
http://www.w3.org/2000/svg svg image/svg+xml
http://www.w3.org/2001/SMIL20/Language smil application/smil+xml
http://www.w3.org/2002/07/owl# Ontology application/owl+xml
http://www.w3.org/2005/11/its its application/its+xml
http://www.w3.org/2005/Atom feed application/atom+xml
http://www.w3.org/2005/SMIL21/Language smil application/smil+xml
http://www.w3.org/2005/sparql-results# sparql application/sparql-results+xml
http://www.w3.org/ns/SMIL smil application/smil+xml
http://xspf.org/ns/0/ playlist application/xspf+xml
urn:HTMLComponent PUBLIC text/x-component
urn:ietf:params:xml:ns:metalink metalink application/metalink4+xml
urn:oasis:names:tc:xliff:document:1.1 xliff application/xliff+xml