The negativeInteger data type is derived from the nonPositiveInteger type. : negativeInteger « XML Schema « XML Tutorial

1. XML Tutorial
2. XML Schema
3. negativeInteger

The value space is the infinite set of integer values less than or equal to 1. 
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>