Wolfgang Plath writes in the preface to volume IX/27/1 of the Neue Mozart-Ausgabe (p.IX): "The notebook turned out to be a crude forgery. There remained an anomymous piano- and music-book from about 1750 of Central German provenance without any relationship to Mozart."

The first number refers to a widespread selection of keybaud pieces from the alleged notebook: https://imslp.org/wiki/Special:ImagefromIndex/113342/qr uu
The second classification refers to a copy of the alleged notebook which is subdivided into suites regarding keys: https://archive.org/details/leopoldmozartsno00moza/page /n11/mode/2up

ABRSM Grade 2 (Associated Board of the Royal Schools of Music, 2015-2016)