GENIE Gridspec Diagrams Discretisation

The following grid tile discretisations should be supported by the gridspec. Currently the gridspec only provides support for logically rectangular grids (LRGs), with limited support for unstructured grids; Balaji proposes that the gridspec should be extended by the appropriate domain experts to cover other discretisations.

<xs:simpleType name="discretization_type">
  <xs:annotation>
    <xs:documentation xml:lang="en">The way a grid tile is split into cells, e.g. logically_rectangular.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="enum_type">
    <xs:enumeration value="logically_rectangular"/>
    <xs:enumeration value="structured_triangular"/>
    <xs:enumeration value="unstructured_triangular"/>
    <xs:enumeration value="unstructured_polygonal"/>
    <xs:enumeration value="pixel-based_catchment"/>
  </xs:restriction>
</xs:simpleType>