TABLE 4 - Conditions per Node for Expanding the Classification Tree,
Node,Condition
1,Year ship was built  ? 1973
2,Year ship was built in (1973–1977]
3,Year ship was built in (1977–1981]
4,Year ship was built > 1981 
5,"Geographic area = {Mediterranean-Black Sea;  China Sea-Japan; Persian Gulf-Bay of Bengal; North Sea, Baltic; N. & S. America, Pacific Coast; Alaska-Bering-USSR Arctic-Iceland; Atlantic Ocean; Gulf of Mexico-W. Indies-Newfoundland}"
6,Geographic area ={Pacific Ocean; Atlantic Ocean;  Red Sea-W. and E. African Coast}
7,Location = {overseas}
8,"Location = {controlled seaways, ports}"
9,Gross tonnage ? 12603
10,"Gross tonnage (12,603–16,705]"
11,"Gross tonnage > 16,705"
12,Geographic area = {Mediterranean-Black Sea; Australia; Alaska-Bering-USSR Arctic-Iceland}
13,"Geographic area = {China Sea-Japan; Persian Gulf-Bay of Bengal; North Sea, Baltic; N. & S. America, Pacific Coast; Atlantic Ocean; Gulf of Mexico-W. Indies-Newfoundland; Pacific Ocean; Atlantic Ocean;  Red Sea-W. and E. African Coast}"