The Platts Electric Substation geospatial data layer contains point features representing electric transmission, sub-transmission, and some distribution substations in North America. These substations are fed by electric transmission and sub-transmission lines and are used to step-up and step-down the voltage of electricity being carried by the lines, or simply to connect together various lines and maintain reliability of supply. These substations can be located on the surface within fenced enclosures, within special purpose buildings, on rooftops (in urban environments), or underground. A substation feature is also used to represent a location where one transmission line "taps" into another.