--- a/xy.py	Wed May 05 18:08:34 2010 +0200
+++ b/xy.py	Wed May 05 18:10:33 2010 +0200
@@ -22,8 +22,11 @@
 from yams import xy
 
 xy.register_prefix('http://purl.org/dc/elements/1.1/', 'dc')
-xy.register_prefix('http://xmlns.com/foaf/0.1/', 'foaf')
-xy.register_prefix('http://usefulinc.com/ns/doap#', 'doap')
+xy.register_prefix('http://xmlns.com/foaf/0.1/',       'foaf')
+xy.register_prefix('http://usefulinc.com/ns/doap#',    'doap')
+xy.register_prefix('http://rdfs.org/sioc/ns#',         'sioc')
+xy.register_prefix('http://www.w3.org/2002/07/owl#',   'owl')
+xy.register_prefix('http://purl.org/dc/terms/',        'dcterms')
 
 xy.add_equivalence('creation_date', 'dc:date')
 xy.add_equivalence('created_by', 'dc:creator')