The duration datatype represents a duration : duration « XML Schema « XML Tutorial

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2. XML Schema
3. duration

<!-- schema -->
<xsd:element name="vacation">
  <xsd:simpleType>
   <xsd:restriction base="xsd:duration">
    <xsd:pattern value="P\d+D\d+H\d+M\d+S"/>
   </xsd:restriction>
  </xsd:simpleType>
</xsd:element>
<!-- instance document -->
<vacation>P10D2H30M45S</vacation>