## 11.4.2.9 MultiPoint Class 

•Constraints on the degree of spatial overlap between elements 

A MultiPoint  is a geometry collection composed of Point  elements. The points are not connected or ordered in any way. 

MultiPoint  Examples 

•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. 

MultiPoint  Properties 

•A MultiPoint  is a zero-dimensional geometry. 

•A MultiPoint  is simple if no two of its Point  values are equal (have identical coordinate values). 

## 11.4.2.10 MultiCurve Class 

•The boundary of a MultiPoint  is the empty set. 

A MultiCurve  is a geometry collection composed of Curve  elements. MultiCurve  is a noninstantiable class. 

MultiCurve  Properties 

•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. 

## 11.4.2.11 MultiLineString Class 

•A MultiCurve  is closed if all of its elements are closed. 

•The boundary of a closed MultiCurve  is always empty. 

A MultiLineString  is a MultiCurve  geometry collection composed of LineString  elements. 

MultiLineString  Examples 

•On a region map, a MultiLineString  could represent a river system or a highway system. 

## 11.4.2.12 MultiSurface Class 

A MultiSurface  is a geometry collection composed of surface elements. MultiSurface  is a noninstantiable class. Its only instantiable subclass is MultiPolygon . 

MultiSurface  Assertions 

•Surfaces within a MultiSurface  have no interiors that intersect. 

