<xs:attribute name="locus" use="required">
  <xs:annotation>
    <xs:documentation>indicates more exactly the aspect concerning which certainty is being expressed: specifically, whether the markup is correctly located, whether the correct element or attribute name has been used, or whether the content of the element or attribute is correct, etc.</xs:documentation>
  </xs:annotation>
  <xs:simpleType>
    <xs:restriction base="xs:token">
      <xs:enumeration value="name">
        <xs:annotation>
          <xs:documentation>uncertainty concerns whether the name of the element or attribute used is correctly applied.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="start">
        <xs:annotation>
          <xs:documentation>uncertainty concerns whether the start of the element is correctly identified.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="end">
        <xs:annotation>
          <xs:documentation>uncertainty concerns whether the end of the element is correctly identified.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="location">
        <xs:annotation>
          <xs:documentation>uncertainty concerns both the start and the end of the element.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="value">
        <xs:annotation>
          <xs:documentation>uncertainty concerns the content (for an element) or the value (for an attribute)</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
    </xs:restriction>
  </xs:simpleType>
</xs:attribute> |