Short answers, pulled from the story.
A maritime boundary is a conceptual division of Earth's water surface areas using physiographical or geopolitical criteria. This line usually bounds areas of exclusive national rights over mineral and biological resources.
The zone extending 12 nautical miles from the baseline constitutes the territorial sea. An area extending 24 nautical miles from the baseline forms the contiguous zone.
A western line of military control between North and South Korea was unilaterally established by the United Nations Command in 1953. Violent clashes in these disputed waters include what are known as the first Yeonpyeong incident and the second Yeonpyeong incident.
Multilateral treaties establish ocean boundaries between specific territories like Australia and New Caledonia in the Coral Sea. The Australia, France Marine Delimitation Agreement consists of 21 straight-line maritime segments defined by 22 individual coordinate points.
The exclusive economic zone extends 200 nautical miles from the baseline except when space between two countries is less than 400 nm. In cases of overlapping zones, the boundary is presumed to conform to the equidistance principle.