architecture and material culture in AAT. The AAT can be used in several ways: at the data entry stage, by catalogers or indexers who are describing works of art, architecture, material culture, archival materials, visual surrogates, or bibliographic materials; as knowledge bases, providing information for researchers; as search assistants to enhance end-user access to online resources; as target for enriching free-text descriptions of cultural objects; as a pivot vocabulary for coreferencing (interlinking) other art vocabularies AAT is available as Linked Open Data at vocab.getty.edu since February 2014 and is updated bi-weekly. Terms The initial core set of terms was derived from authority lists and the literature of art and architectural history; this core set was reviewed, approved and added to by an advisory team made up scholars from all relevant disciplines, including art and architectural historians, architects, librarians, visual resource curators, archivists, museum personnel, and specialists in thesaurus construction. Its hierarchy was inspired by the Medical Subject Headings. All eras from antiquity to the present are covered, and it is not limited geographically. As of January 2007, the AAT contained approximately 131,000 terms. While the thesaurus contains many variations on a term, such as singular and plural forms, spelling variants, various forms of speech, and synonyms, one is always flagged as the preferred term. Terms are updated biweekly and regular users are encouraged to propose new terms. In 2015 AAT contains 354,000 terms. They are available in 4 major languages (English, Dutch, Spanish and Chinese), and some terms in various native languages. Design The AAT is a faceted classification system as well as a hierarchical one. There are seven facets: Associated Concepts – abstract concepts, such as beauty, balance, connoisseurship, metaphor, freedom, socialism (Hierarchy: Associated concepts) Physical Attributes – perceptible or measurable characteristics such as size, shape, chemical properties, texture and hardness, such as strapwork, borders, round, waterlogged, brittleness. (Hierarchies: Attributes and Properties, Conditions and Effects, Design Elements, Color) Styles and Periods – stylistic groupings and distinct chronological periods, such as French, Louis XIV, T'ang Dynasty, Chippendale (Hierarchy: Styles and Periods) Agents – people, groups of people, and organizations such as printmakers, landscape architects, corporations, religious orders. (Hierarchies: People, Organizations) Activities – areas of endeavor, physical and mental actions or methods, such as archaeology, engineering, analyzing, contests, exhibitions, running, drawing (image-making), corrosion. (Hierarchies: Disciplines, Functions, Events, Physical and Mental Activities, Processes and Techniques) Materials – physical substances, such as iron,