Depending on context, a group of connected conses can be viewed in a variety of different ways. A variety of operations is provided to support each of these various views.
A tree is a binary recursive data structure made up of conses and atoms: the conses are themselves also trees (sometimes called “subtrees” or “branches”), and the atoms are terminal nodes (sometimes called leaves). Typically, the leaves represent data while the branches establish some relationship among that data.
Lists are sometimes viewed as sets by considering their elements unordered and by assuming there is no duplication of elements.
Except as explicitly specified otherwise, any standardized function that takes a parameter that is required to be a list should be prepared to signal an error of type type-error if the value received is a dotted list.