An Unstructured_mesh is a Mesh that is defined as a set of instances of Region.
An Unstructured_mesh specfies a sequence for the instances of Region.
For many types of engineering analysis, an Unstructured_mesh is a set of instances of Vertex_defined_cell. In this case, the connectivity of the cells can be deduced from their vertices.
An Unstructured_mesh may specify a sequence for the union of the vertices of the instances of Region, if each Region is a Vertex_defined_cell.
The sequence for the control values specified for a Mesh_function shall be consistent with sequence for the instances of Region or Vertex (depending upon the nature of the function).
NOTE - The sequence for the instances of Region or Vertex does not necessarily have any physical significance.
EXPRESS specification:
*) ENTITY Mesh_cell SUBTYPE OF (Mesh); cells : LIST[1,?] OF Region; vertices : OPTIONAL LIST[1,?] OF Vertex; END_ENTITY; (*
Attribute definitions:
cells: The instances of Region that make up the Unstructured_mesh.
vertices: The instances of Vertex that are referenced by instances of Vertex_defined_cell within the Unstructured_mesh.