Validace vůči více schématům najednou

<rules xmlns="http://purl.oclc.org/dsdl/nvdl/ns/structure/1.0">
  <namespace ns="http://www.w3.org/1999/xhtml">
    <validate schema="xhtml1-transitional.xsd"/>
    <validate schema="xhtml.sch"/>
  </namespace>
</rules>