The OpenGIS Geometry Model 11.4.2.9 MultiPoint Class 11.4.2.10 MultiCurve Class 11.4.2.11 MultiLineString Class 11.4.2.12 MultiSurface Class •Constraints on the degree of spatial overlap between elements •On a world map, a  MultiPoint  could represent a chain of small islands. •On a city map, a  MultiPoint  could represent the outlets for a ticket office. •A  MultiPoint  is a zero-dimensional geometry. •A  MultiPoint  is simple if no two of its  Point  values are equal (have identical coordinate values). •The boundary of a  MultiPoint  is the empty set. •A  MultiCurve  is a one-dimensional geometry. •A  MultiCurve  is simple if and only if all of its elements are simple; the only intersections between any two elements occur at points that are on the boundaries of both elements. •A  MultiCurve  boundary is obtained by applying the “mod 2 union rule”  (also known as the “odd-even rule” ): A point is in the boundary of a  MultiCurve  if it is in the boundaries of an odd number of  Curve elements. •A  MultiCurve  is closed if all of its elements are closed. •The boundary of a closed  MultiCurve  is always empty. •On a region map, a  MultiLineString  could represent a river system or a highway system. •Surfaces within a  MultiSurface  have no interiors that intersect. MultiSurface  Assertions A  MultiSurface  is a geometry collection composed of surface elements.  MultiSurface  is a noninstantiable class. Its only instantiable subclass is  MultiPolygon . MultiLineString  Examples A  MultiLineString  is a  MultiCurve  geometry collection composed of  LineString  elements. MultiCurve  Properties A  MultiCurve  is a geometry collection composed of  Curve  elements.  MultiCurve  is a noninstantiable class. MultiPoint  Properties A  MultiPoint  is a geometry collection composed of  Point  elements. The points are not connected or ordered in any way. MultiPoint  Examples 2056