•Surfaces within a MultiSurface  have boundaries that intersect at most at a finite number of points. 

## 11.4.2.13 MultiPolygon Class 

A MultiPolygon  is a MultiSurface  object composed of Polygon  elements. 

MultiPolygon  Examples 

•On a region map, a MultiPolygon  could represent a system of lakes. 

MultiPolygon  Assertions 

•A MultiPolygon  has no two Polygon  elements with interiors that intersect. 

•A MultiPolygon  has no two Polygon  elements that cross (crossing is also forbidden by the previous assertion), or that touch at an infinite number of points. 

•A MultiPolygon  may not have cut lines, spikes, or punctures. A MultiPolygon  is a regular, closed point set. 

•A MultiPolygon  that has more than one Polygon  has an interior that is not connected. The number of connected components of the interior of a MultiPolygon  is equal to the number of Polygon  values in the MultiPolygon . 

MultiPolygon  Properties 

•A MultiPolygon  is a two-dimensional geometry. 

•A MultiPolygon  boundary is a set of closed curves ( LineString  values) corresponding to the boundaries of its Polygon  elements. 

•Each Curve  in the boundary of the MultiPolygon  is in the boundary of exactly one Polygon  element. 

•Every Curve  in the boundary of an Polygon  element is in the boundary of the MultiPolygon . 

## 11.4.3 Supported Spatial Data Formats 

Two standard spatial data formats are used to represent geometry objects in queries: 

•Well-Known Text (WKT) format 

•Well-Known Binary (WKB) format 

Internally, MySQL stores geometry values in a format that is not identical to either WKT or WKB format. (Internal format is like WKB but with an initial 4 bytes to indicate the SRID.) 

There are functions available to convert between different data formats; see Section 12.17.6, “Geometry Format Conversion Functions” . 

## Well-Known Text (WKT) Format 

The following sections describe the spatial data formats MySQL uses: 

•Well-Known Text (WKT) Format 

•Well-Known Binary (WKB) Format 

•Internal Geometry Storage Format 

