XML Tutorial/XML Schema/negativeInteger

The negativeInteger data type is derived from the nonPositiveInteger type.

The value space is the infinite set of integer values less than or equal to ? 
The lexical space is a finite-length sequence of decimal digits preceded by a -.

<!-- schema -->
<xsd:simpleType name="myType">
  <xsd:restriction base="xsd:negativeInteger">
   <xsd:pattern value="-\d{2}"/>
  </xsd:restriction>
</xsd:simpleType>
<!-- instance document -->
<myType>-49</myType>