Opus number developed other catalogue-number systems; among them the "Bach-Werke-Verzeichnis" (BWV-number), and the "Köchel-Verzeichnis" (K- and KV -numbers) with which are organised the works of Johann Sebastian Bach and Wolfgang Amadeus Mozart, respectively. In the classical period, the Latin word "opus" ("work", "labour") was used to identify, list, and catalogue a work of art. By the 15th and 16th centuries, the word "opus" was used by Italian composers to denote a specific musical composition, and by German composers for collections of music. In compositional practise, numbering musical works in chronological order dates from 17th century Italy, especially Venice. In common usage, the
Chess composer Chess composer A chess composer is a person who creates endgame studies or chess problems. Chess composers usually specialize in a particular genre, e.g. endgame studies, twomovers, threemovers, moremovers, helpmates, selfmates, or fairy problems. Moreover, composers have their own preferred style of composing, allowing their sorting according to composition schools. Some chess composers produce huge numbers of chess compositions, while others try to achieve as much quality as possible and present new works only rarely. It is possible for chess composers to gain official FIDE titles, usually for a given number of problems published in FIDE Albums. For example, Milan