What is indicated by a WoO number in particular compositions Beethoven?

WoO stands for "Werke ohne Opuszahl", which means "works without opus number". It is used to identify compositions by Ludwig van Beethoven that were not assigned an opus number by the composer himself. These works may include early compositions, sketches, fragments, and other pieces that were not published or officially released during Beethoven's lifetime.

The WoO numbering system was introduced by Beethoven's biographers and scholars to organize and catalogue his vast body of work. It is used alongside the more common opus number system, which was used by Beethoven to designate his published compositions. The WoO numbers are assigned sequentially, and they provide a way to identify and refer to specific compositions that do not have an opus number.

For example, the composition known as the "Für Elise" bagatelle is identified as WoO 59. This means that it is a work by Beethoven that does not have an opus number, and it is the 59th entry in the WoO catalogue.

The WoO numbering system is important for researchers, musicologists, and performers who study and perform Beethoven's music. It allows them to identify and access specific compositions that may not be as well-known or widely published as his numbered works.