def to_xml(options = {})
      xml = options[:builder] ||= Builder::XmlMarkup.new
      xml.instruct! unless options[:skip_instruct]
      xml.osm(:generator => "rosemary v#{Rosemary::VERSION}", :version => Rosemary::Api::API_VERSION) do
        xml.relation(attributes) do
          members.each do |member|
            member.to_xml(:builder => xml, :skip_instruct => true)
          end
          tags.to_xml(:builder => xml, :skip_instruct => true)
        end
      end
    end
def to_xml(options = {})
      xml = options[:builder] ||= Builder::XmlMarkup.new
      xml.instruct! unless options[:skip_instruct]
      xml.osm(:generator => "rosemary v#{Rosemary::VERSION}", :version => Rosemary::Api::API_VERSION) do
        xml.relation(attributes) do
          members.each do |member|
            member.to_xml(:builder => xml, :skip_instruct => true)
          end
          tags.to_xml(:builder => xml, :skip_instruct => true)
        end
      end
    end
Return XML for this relation. This method uses the Builder library.
 The only parameter ist the builder object.