To specify a constraint specific to Polygons, it is useful to introduce the concept of a linear ring:

  • A linear ring is a closed LineString with four or more positions
  • The first and last positions are equivalent
  • A linear ring is the boundary of a surface
  • A linear ring must follow the right-hand rule. Exterior rings are counterclockwise, and holes are clockwise.

For type Polygon, the coordinates member must be an array of linear ring coordinate arrays.

No holes:

With holes: