Outliner
（重定向自Outline processor）
An outliner (or outline processor) is a specialized type of word processor used to create, build, modify, and maintain outlines. It is a computer program, or part of one, used for displaying, organizing, and editing hierarchically arranged text in an outline's tree structure. Textual information is contained in discrete sections called "nodes", which are arranged according to their topic-subtopic (parent-child) relationships, sort of like the members of a family tree. When loaded into an outliner, an outline may be collapsed or expanded to display as few or as many levels as desired.