<simpleType name="OffsetDirectionEnumType">
  <annotation>
    <documentation>The side of a linear element on which lateral offsets are positive, looking along the element from its first to its last coordinate in gml:posList. Offsets on the other side are negative, and zero is on the centerline.</documentation>
  </annotation>
  <restriction base="string">
    <enumeration value="right">
      <annotation>
        <documentation>Positive offset is to the right when looking along the linear element. Standard for terrestrial applications such as transects, pipelines and road alignments.</documentation>
      </annotation>
    </enumeration>
    <enumeration value="left">
      <annotation>
        <documentation>Positive offset is to the left when looking along the linear element.</documentation>
      </annotation>
    </enumeration>
    <enumeration value="starboard">
      <annotation>
        <documentation>Positive offset is to starboard, the right side when facing the bow. Marine convention for geophysical tracklines and marine surveys; equivalent to right.</documentation>
      </annotation>
    </enumeration>
    <enumeration value="port">
      <annotation>
        <documentation>Positive offset is to port, the left side when facing the bow. Marine convention for geophysical tracklines; equivalent to left.</documentation>
      </annotation>
    </enumeration>
  </restriction>
</simpleType>