/usr/lib/ruby/1.8/xsd/ is in libruby1.8 1.8.7.352-2ubuntu1.6.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/1.8/xsd/charset.rb
/usr/lib/ruby/1.8/xsd/codegen/
/usr/lib/ruby/1.8/xsd/codegen.rb
/usr/lib/ruby/1.8/xsd/codegen/classdef.rb
/usr/lib/ruby/1.8/xsd/codegen/commentdef.rb
/usr/lib/ruby/1.8/xsd/codegen/gensupport.rb
/usr/lib/ruby/1.8/xsd/codegen/methoddef.rb
/usr/lib/ruby/1.8/xsd/codegen/moduledef.rb
/usr/lib/ruby/1.8/xsd/datatypes.rb
/usr/lib/ruby/1.8/xsd/datatypes1999.rb
/usr/lib/ruby/1.8/xsd/iconvcharset.rb
/usr/lib/ruby/1.8/xsd/mapping.rb
/usr/lib/ruby/1.8/xsd/namedelements.rb
/usr/lib/ruby/1.8/xsd/ns.rb
/usr/lib/ruby/1.8/xsd/qname.rb
/usr/lib/ruby/1.8/xsd/xmlparser/
/usr/lib/ruby/1.8/xsd/xmlparser.rb
/usr/lib/ruby/1.8/xsd/xmlparser/parser.rb
/usr/lib/ruby/1.8/xsd/xmlparser/rexmlparser.rb
/usr/lib/ruby/1.8/xsd/xmlparser/xmlparser.rb
/usr/lib/ruby/1.8/xsd/xmlparser/xmlscanner.rb