1. layered structure; layered system; stratification; hierarchical structure
Wikipedia definition
2. HierarchyA hierarchy is an arrangement of items (objects, names, values, categories, etc. ) in which the items are represented as being "above," "below," or "at the same level as" one another. Abstractly, a hierarchy is simply an ordered set or an acyclic directed graph. A hierarchy (sometimes abbreviated HR) can link entities either directly or indirectly, and either vertically or horizontally.
Read “Hierarchy” on English Wikipedia
Read “階層構造” on Japanese Wikipedia
Read “Hierarchy” on DBpedia


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