elementSpecs trying to purify tei_xinclude.odd (or indeed add XInclude to my own odd)

AddingXInclude.odd

        <elementSpec ident="include" ns="http://www.w3.org/2001/XInclude" mode="add">
          <desc xml:lang="en" versionDate="2014-01-12">The W3C XInclude element</desc>
          <classes>
            <memberOf key="model.common"/>
            <memberOf key="model.teiHeaderPart"/>
          </classes>
          <content>
            <elementRef key="fallback" minOccurs="0" maxOccurs="1"/>
          </content>
          <attList>
            <attDef ident="href">
              <desc xml:lang="en" versionDate="2014-01-12">pointer to the resource being included</desc>
              <datatype>
                <dataRef key="teidata.pointer"/>
              </datatype>
            </attDef>
            <attDef ident="parse" usage="opt">
              <defaultVal>xml</defaultVal>
              <valList type="closed">
                <valItem ident="xml"/>
                <valItem ident="text"/>
              </valList>
            </attDef>
            <attDef ident="xpointer" usage="opt">
              <datatype>
                <textNode/>
              </datatype>
            </attDef>
            <attDef ident="encoding" usage="opt">
              <datatype>
                <textNode/>
              </datatype>
            </attDef>
            <attDef ident="accept" usage="opt">
              <datatype>
                <textNode/>
              </datatype>
            </attDef>
            <attDef ident="accept-charset" usage="opt">
              <datatype>
                <textNode/>
              </datatype>
            </attDef>
            <attDef ident="accept-language" usage="opt">
              <datatype>
                <textNode/>
              </datatype>
            </attDef>
          </attList>
        </elementSpec>

        <elementSpec ident="fallback" ns="http://www.w3.org/2001/XInclude" mode="add">
          <desc  xml:lang="en" versionDate="2014-01-12">Wrapper for fallback elements if an XInclude fails</desc>
          <content>
            <alternate>
              <textNode/>
              <anyElement/>
            </alternate>
            </content>
        </elementSpec>

@lb42 points out that I should change these attribute datatypes to

              <datatype>
                     <dataRef key="teidata.text"/>
              </datatype>

which does seem right. But I'm still getting the same schematron error in oXygen: datatype content must be in the namespace ''