Shorelines, including sides of tidal rivers, are known as natural feature boundaries when they form the boundaries of land parcels. In the context of Survey Services practice, these boundaries are defined by the 2.515m High Water Mark (HWM) above the Chart Datum. The reduced level of the 2.515m HWM is 0.960m above Mean Sea Level which is the Survey Services precise levelling datum. By definition, "land" is from and above the 2.515m HWM while "foreshore" or "seabed" is below this line.