The unsignedInt data type is derived from the unsignedLong type. : unsignedInt « XML Schema « XML Tutorial

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The value space is the set of integers greater than or equal to 0 and less than or equal to 4294967295. 
The lexical space is a finite-length sequence of decimal digits.

<!-- schema -->
<xsd:simpleType name="grains_of_sand">
  <xsd:restriction base="xsd:unsignedInt">
   <xsd:maxInclusive value="4000000000"/>
  </xsd:restriction>
</xsd:simpleType>
<!-- instance document -->
<grains_of_sand>4000000000</grains_of_sand >