<xs:simpleType name="ChannelIndexType">
  <xs:annotation>
    <xs:documentation>Specifies the type of index used by the channel.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="eml:TypeEnum">
    <xs:enumeration value="measured depth">
      <xs:annotation>
        <xs:documentation>Measured depth.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="true vertical depth">
      <xs:annotation>
        <xs:documentation>True vertical depth.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="pass indexed depth">
      <xs:annotation>
        <xs:documentation>An index value that includes pass, direction, and depth values This can only refer to measured depths.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="date time">
      <xs:annotation>
        <xs:documentation>Date with time.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="elapsed time">
      <xs:annotation>
        <xs:documentation>Time that has elapsed</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="temperature">
      <xs:annotation>
        <xs:documentation>Temperature.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
    <xs:enumeration value="pressure">
      <xs:annotation>
        <xs:documentation>Pressure.</xs:documentation>
      </xs:annotation>
    </xs:enumeration>
  </xs:restriction>
</xs:simpleType>