OpenGIS implementation specification for coordinate transformation services. This implementation specification provides interfaces for general positioning, coordinate systems, and coordinate transformations. Coordinates can have any number of dimensions. So this specification can handle 2D and 3D coordinates, as well as 4D, 5D etc.

All interfaced objects are immutable. This means that implementations must promise not to change an object's internal state once they have handed out an interface pointer. All mutable entities are implemented with classes.

Since all interfaced objects are specified to be immutable, there do not need to be any constraints on operation sequencing. This means that these interfaces can be used in parallel computing environments (e.g. internet servers).