A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present geospatial data. Typically, a GIS uses a spatio-temporal location as the key index variable for all other information and calculations. A GIS can relate otherwise unrelated information (e.g., geographic data) by using location as the key index variable. Thus, any variable that can be located spatially can be referenced using a GIS. Locations in Earth space-time may be recorded as dates/times of occurrence, and x, y, and z coordinates representing longitude, latitude, and elevation, respectively.