public interface ICrsPrimeMeridian : ICrsInfo

Public Interface ICrsPrimeMeridian
	Inherits ICrsInfo

public interface class ICrsPrimeMeridian : ICrsInfo

type ICrsPrimeMeridian =  
    interface
        interface ICrsInfo
    end

Latitude has a natural starting point in the equator. There is no natural starting point for longitude, known as the prime meridian, which is arbitrarily defined. Historically national systems usually adopted their national astronomical observatory as the starting point for longitude. The meridian through Greenwich has been accepted as the international norm for over a century, but its adoption for geodetic purposes has lagged somewhat. Longitudes based on other prime meridians, for example Paris, remain in use today. Longitude is unambiguous only when the prime meridian is defined.