/ @ [ ] When lang attribute is present, the value must equal the value of xml:lang. RDDL resources must be within the html body. There should be at least one RDDL resource in the body. The element rddl:resource should contain only the attributes id, xml:base, xml:lang, xlink:href, xlink:arcrole, xlink:role, xlink:href. The rddl:resource element should only have child elements from the XHTML and RDDL namespaces. RDDL resources are simple Xlinks. xlink:embed,xlink:show are not used. The value of xlink:role cannot be a relative URI reference. The value of xlink:arcrole cannot be a relative URI reference. A rddl:resource should have a description. Parent element [ ] must be either Flow.mix or Block.mix, Element [ ]