...which is the order of the four letters of the Name, blessed be He. The four letters of the Name of Havayah, blessed be He, contain all the ten Sefirot according to their essential division into five Partzufim. Thus the cusp of the Yud is Arich Anpin (=Keter) while its main body is Abba (=Chochmah). The first Heh is Imma (=Binah), the Vav is Zeir Anpin (=Chessed-Gevurah-Tiferet-Netzach-Hod-Yesod), while the final Heh is Nukva (=Malchut).
Part 2: And this is the order that governs the musical notes, vowel signs, crowns and letters through the four letters... The musical notes, vowel signs, crowns and letters are all separate functions, each of which emerges from its own particular source. Yet all are governed by the overall order, which is that of the Name of Havayah, blessed be He....and the four names... namely AV, SaG, MaH and BaN, the four expansions of the Name, which also correspond to the four letters