This operation is only supported with ArcGIS Server v10.0 and higher.

The SpatialRelDescription is a nine character string describing the spatial relationships to be tested by the spatial filter. The SpatialRelDescription allows the comparison of any and all possible spatial intersections between two shapes. The intersection of each shapes boundary, interior, and exterior can be tested to allow the confirmation or various spatial relationships. All other spatial enumerators can be duplicated using this enumerator.

Shape relationships are defined by the intersection of their boundary, interior, and exterior.

Interior: The interior of a shape is defined as the entire shape minus its boundary. All shapes have interior.

Boundary: Linear and area shapes have boundary, but point shapes do not. The boundary of linear shapes consists of the end points of all linear parts. The boundary of area shapes consists of the linear boundary of the polygon shell(s).

Exterior: The area outside a shape. All shapes have an exterior.

Each element for the first shape, the query geometry, may be tested against each element of the second shape, the requested geometry, giving nine possible spatial intersections as listed in the table below:

The nine-characters string expected by ISpatialFilter::SpatialRelDescription, is used to specify whether the intersection of each of the elements in the array is true (T), false (F), or not tested (*).

For instance, in 'FFFTTT***', relationships 1-3 must be false, relationships 4-6 must be true, and relationships 7-9 are not tested.

Note that any two shapes' exteriors always intersect.

The following are some SpatialRelDescription string examples:

• Shares a boundary: '****T***'
• Shares a boundary and interiors intersect: 'T***T****'
• Shares a boundary and interiors do not intersect: 'F***T****'
• Does not touch the boundary and interiors intersect: 'T***F****'

For more information on this topic go to the following discusion on the Shape Comparison Language.