baseline
the line from which the seaward limits of a state's territorial sea and certain other maritime zones of jurisdiction are measured; normally, a sea baseline follows the low-water line of a coastal state
en-GB/ˈbeɪslaɪn/
en-US/ˈbeɪsˌlaɪn/
the line from which the seaward limits of a state's territorial sea and certain other maritime zones of jurisdiction are measured; normally, a sea baseline follows the low-water line of a coastal state