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
Austrian National Library also successfully introduced the card index. This facilitated the continuous updating of the inventory. After the Holy Roman Empire was dissolved by Napoleon and the Austrian Empire proclaimed in its place, the library was again reorganized. Under custodian Paul Strattmann, the library received a program for the first time which described its order; the library gained a three-way viewpoint: The collection politics of the Imperial Library separated at the beginning the 19th century appreciably due to the requirements of the representation and its attention to scientific works. The multinational condition of the Austrian Empire brought with itself that, not only