Of the terms - Land and Landscape

In Agrovoc, Landscape is an NT under under Land. For indexing, such type of grouping was found to be convenient. But in the revised version, only `is a' relation and `instance of' relation define the BT/NT relationship.

Since, the relation between Land and Landscape is neither an `is a' relation nor `an instance' relation, Landscape cannot be an NT under Land. It can at best be an RT.

Then, what should be the BT for Landscape? Should it be Physiographic features? Please comment.

(Note: The UF ref. for Physiographic features is Physical landscape features, i.e. Physical landscape features USE 5834 - Physiographic features)