Terminology
The terms boundary, frontier and border are often used as if they were interchangeable, but they are also terms with precise meanings.
A boundary is a line. The terms "frontier", "borderland" and "border" are zones of indeterminate width. Such areas forms the outermost part of a country. Borders are bounded on one side by a national boundary. There are variations in the specific terminology of maritime boundary agreements which have been concluded since the 1970s. Such differences are less important than what is being delimited.
Read more about this topic: Maritime Boundaries