  <define name='svg.feMorphology.content'>
    <zeroOrMore>
      <choice>
        <ref name='animate'/>
        <ref name='set'/>
      </choice>
    </zeroOrMore>
  </define>

  <define name='feMorphology'>
    <element name='feMorphology'>
      <ref name='attlist.feMorphology'/>
      <ref name='svg.feMorphology.content'/>
    </element>
  </define>

  <define name='attlist.feMorphology' combine='interleave'>
    <ref name='svg.Core.attrib'/>
    <ref name='svg.FilterColor.attrib'/>
    <ref name='svg.FilterPrimitiveWithIn.attrib'/>
    <optional>
      <attribute name='operator' a:defaultValue='erode'>
        <choice>
          <value>erode</value>
          <value>dilate</value>
        </choice>
      </attribute>
    </optional>
    <optional>
      <attribute name='radius'>
        <ref name='NumberOptionalNumber.datatype'/>
      </attribute>
    </optional>
  </define>
