The Attributes and Properties hierarchy contains terms for inherent characteristics, especially physical characteristics of materials and objects. Excluded are terms for colors and color properties, which are found in the separate Color hierarchy. In common usage, the distinction between which characteristics may be called "attributes" and which "properties" is not always clear, thus a separation between the two has not always been made in the hierarchy. As a general guideline, "attributes" refers to characteristics of individual objects, items, or entities, and the terms are mostly used to describe the thing; they often are readily apparent, though not quantifiable by an established standard. "Properties" refers here to characteristics that suggest how a material, or sometimes a grouping of things, will respond under certain conditions; they often are quantifiable, though often are not apparent without examination or testing. Relation to other hierarchies: Other terms that may be considered as attributes and may be used to describe objects are available in the form of alternate descriptors in other hierarchies (e.g., "carved," alternate of "carving"; "wooden," alternate of "wood"). Descriptors for color names are found in the color hierarchy. Certain physical phenomena that are closely associated with physical and chemical properties (e.g., "luminescence") are found in the Associated Concepts hierarchy. Expressions that describe effects of particular physical circumstances on materials or objects appear in the Conditions and Effects hierarchy (e.g., "cracks"). Descriptive characteristics appear also in various other hierarchies as parts of bound compound terms (e.g., "split-level houses").
