Object tree

From IFWiki

An abstract programming structure denoting the containment of objects. This is generally used in manipulation of objects (as Inform 6 and Hugo do with "move chalk to player" and "remove hat") and in listing a room's contents, especially if a certain order is necessary. An object tree is generally described in programming in terms of "parentage". For example, if the player character is holding a piece of chalk, the player character is considered the "parent" of the chalk since the chalk object is contained in the player character object.