D-B Am.B 462
From pipe-organ.wiki
D-B Am.B 462 is a manuscript in Staatsbibliothek, Berlin. It was written around 1770 and is a copy of B-Bc 26659.
References
Beckmann, Klaus (editor), D. Buxtehude: Sämtliche Orgelwerke. Wiesbaden: Breitkopf & Härtel, 1997. Source E3 (the signature is written Mus.ms. Am. 462)