Dance only acquired a fully comprehensive system of notation during the 20th century, which means that many ballets prior to this date were either lost or handed down in partial form. The fact that movement requires both spatial and temporal notation makes it hard to record accurately on paper although attempts to do so date back to the late 15th century. In early notation, letters were used to denote various steps, e.g. R for reverence, s for single, d for double. This method was used in two surviving manuscripts: Margherita d'Austria's Livre des Basses Danses (c.1460) and L'Art et instruction de bien danser (c.1488). More elaborate descriptions of the manner in which dances should be performed were published in books by the leading dancing masters of the 16th and 17th centuries, the most famous of these being Arbeau's L'Orchésographie (Langres, 1588). The first sophisticated attempt at a system was published by Feuillet in his Chorégraphie ou L'Art de décrire la danse par caractères, figures et signes demonstratifs (Paris, 1700), which was based on ideas originated by Beauchamps. This became popular all round Europe as a means of recording and teaching dances. It depicted the floor patterns of the dances, adding signs for the direction of each step as well as for turns, beats, and other details of footwork. The problem of notating body and arm positions was addressed in the 19th century by Saint-Léon in his Sténochorégraphie (Paris, 1852) and by the dancing master Albert Zorn in his Grammatik der Tanzkunst (Leipzig, 1887), both of whom used stylized stick figures to record whole body movement. The idea of writing down dance in a manner similar to music was first developed by B. Klemm in 1855 and further developed by the Russian dancer Stepanov. In his Alphabet des mouvements du corps humain (Paris, 1892) he placed movement symbols on a special stave while recording the floor patterns above it. This system was taught at the Imperial Ballet and was used by Sergeyev to notate the Petipa and Ivanov ballets which he later mounted in the West. During the 20th century the necessity for recording styles of movement other than ballet led to attempts at more rigorous and complete notation based on abstract symbols. The most famous of these was originated by Laban and first published in 1926 in his Choreographie. Now widely referred to as Labanotation this system uses a vertical staff to represent the body and has symbols that indicate not only the position but also the direction, duration, and the quality of any movement. The system has since been refined and elaborated by many scholars and is so accurate that any dance can be protected by the laws of copyright. Hitherto any dancer or choreographer could stage someone else's work with few restrictions, hence the number of 19th-century productions around Europe and America of ballets originally created by Taglioni, Perrot, etc. Another widely used system is that developed by R. and J. Benesh. This began as a shorthand for notating ballets and was first published as An Introduction to Benesh Dance Notation (London, 1956). Now termed ‘choreology’, the Benesh system uses a five-line musical stave running horizontally across the page with abstract stick figures indicating the position of the body and special symbols indicating timing, direction, etc. Though most widely used in ballet companies, choreology has subsequently evolved to deal with non-classical movement also, and together with Labanotation is the most internationally used system. Other systems have been less widely adopted, for example N. Eshkol and A. Wachman's, published in Movement Notation (London, 1958), which is based on a mathematical record of the degree of rotation made by each of the moving parts of the body. Recently the availability of simple and inexpensive video equipment has provided another means of recording dances.