Bach's autograph of this earliest model does not survive. This version is found in the manuscripts of later generations, such as P 563 produced by the copyist worked for C. P. E. Bach in his Hamburg days.
This version is known through the copy (P 595) made by J. F. Agricola, who began his study with Bach on that year.
Based on the intermediate version, Bach presumably transposed the piece to C# major on this score, while composing the 5 bar extension (bb. 25-29) where the subject appears in augmented form. Bach revised the piece several times, introducing further demisemiquaver figurations from bar 8 onwards .