<xsd:attributeGroup name="duration">
  <xsd:annotation>
    <xsd:documentation>
      <type>Attlist</type>
      <name>duration</name>
      <comment>The duration attribute is used to specify a duration when either the start or the end event of a time interval is not known.</comment>
    </xsd:documentation>
  </xsd:annotation>
  <xsd:attribute name="duration" type="xsd:duration"/>
</xsd:attributeGroup> |