Classification tree technical terms
Arc
Part of a branch linking a parent node to a child node. In a classification tree, an arc from node A to node B represents the fact that node B is a subclass or member of class A. Such arcs are sometimes called is-a links (because B is-a A).
Inheritance
The inheritance of a class is the set of features owned by the class's ancestors. The total set of features owned by a class is its inheritance plus its local features. Classification trees are concise in that only local features need to be explicitly listed at each node.
Label
The text on a node. A label may have two parts. The first part, displayed on the tree in normal type, identifies the name of the class. The second part, displayed in italic type, identifies the special (local) features of the class and must use feature syntax. When entering or editing a label, italics are not used - instead, you must be sure to enclose the features in round brackets. Features are optional (but recommended) depending on the setting of 'Classification syntax' in the Settings dialogue.
Node
A square with a text label. A node represents a class of things or perhaps (in the case of a leaf node) a member of a class of things, i.e. an individual instance of a class. The leftmost node in a tree is called the root node.