BWV stands for Bach-Werke-Verzeichnis which means a "Catalog of BachÕs Work." The Bach-Werke-Verzeichnis was put together and edited by Wolfgang Schmieder. ItÕs a thematic catalog, not a chronological numbering. You can tell nothing from the BWV number about when a work by Bach was written. But, if you know the system you can tell what kind of work it is. The first set of numbers are the cantatas and then you have a set of numbers for concertos, for instrumental works, for chorals, for organ works, and so on.