Spatial Reference Model
The Spatial Reference Model (SRM):
CSs, RDs and RDSs for defining spatial relationship(s);
Time Coordinate Systems for defining and comparing when events occur;
ORMs that bind RDSs to spatial objects;
SRF Classes and SRF Sets that combine ORMs and CSs to define a spatial referencing system;
Spatial operations for positions, directions, distances and other spatial information within or between different SRF Classes;
Spatial relationships among SRF Classes to support spatial operations;
An Application Program Interface for the spatial operations; and,
Supporting concepts including quality assurance, conformance and registration.