Data are often assumed to be the least abstract concept, information the next least, and knowledge the most abstract. In this view, data becomes information by interpretation; e.g., the height of Mount Everest is generally considered data, a book on Mount Everest geological characteristics may be considered information, and a climber's guidebook containing practical information on the best way to reach Mount Everest's peak may be considered knowledge. Information bears a diversity of meanings that ranges from everyday usage to technical use. This view, however, has also been argued to reverse the way in which data emerges from information, and information from knowledge. Generally speaking, the concept of information is closely related to notions of constraint, communication, control, data, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation. Beynon-Davies uses the concept of a sign to differentiate between data and information; data are a series of symbols, while information occurs when the symbols are used to refer to something.