Telemann-Werke-Verzeichnis

The Telemann-Werke-Verzeichnis (Telemann Works Catalogue), abbreviated TWV, is the numbering system identifying compositions by Georg Philipp Telemann, published by musicologist Martin Ruhnke.
The prefix TWV is generally followed by a genre number, a letter indicating the key (in some cases), and a work number. The genre number indicates the general type or medium of the work. A major key is in upper case, a minor key in lower case. The second number is the work's number within the genre. For example, Telemann's "Concerto polonois in B flat major for strings and basso continuo" is TWV 43:B3. His "Orchestral suite in D major" is TWV 55:D18, and his "Overture in G minor" is TWV 55:g4.
Vocal works were catalogued in a similar way by Werner Menke in the Telemann-Vokalwerke-Verzeichnis (Telemann Vocal Works Catalogue), abbreviated TVWV. For example, Telemann's "Johannes-Passion" is TVWV 5:42. His "Times of the Day" cantata is TVWV 20:39.
Genre numbering.
Genres of vocal works are numbered from 1 to 25, and usually prefixed by TVWV. Genres of instrumental works are numbered from 30 to 55.
The genres are numbered as follows:
Instrumental music (TWV).
Mixed collections: