[PetahW]

Interesting - Here's the table from Ludwig Olsen's book:

Code / Manufacturer
ar = Mauser-Werke AG, Werk Borsigwalde, Berlin-Borsigwalde, Eichborndamm
ax = Feinmechanische Werke GmbH, Erfurt, Altonaerstr.
bcd = Gustloff Werke, Werk Wiemar, Weimar
bcd/ar= Dual code; denotes manufacture jointly by Gustloff Werke in Weimar, and Mauser-Werke AG, Berlin
bnz = Steyr-Daimler-Puch AG, Werk Steyr, Steyr, Austria
byf = Mauser-Werke AG, Oberndorf a./N
ce = J.P. Sauer & Sohn, Suhl
dot = Waffenwerke Bruenn AG, Brno, Czechoslovakia
dou = Waffenwerke Bruenn AG, Werk Bystrica
duv = Berlin-Luebecker Maschinenfabriken, Werk Luebeck
svw = Late code for Mauser-Werke AG, Oberndorf a./N
swp = Late code for Waffenwerke Bruenn AG, Brno, Czechoslovakia
S/27 = Erfurter Maschinenfabrik (ERMA); came under same management as Feinmechanische Werke GmbH
S/27G = Erfurter Maschinenfabrik (ERMA); came under same management as Feinmechanische Werke GmbH
S/42 = Mauser-Werke AG, Oberndorf a./N, early code
S/42G = Mauser-Werke AG, Oberndorf a./N, production in 1935
S/42K = Mauser-Werke AG, Oberndorf a./N, production in 1934
S/147 = J.P. Sauer & Sohn, Suhl
S/147G = J.P. Sauer & Sohn, Suhl
S/147K = J.P. Sauer & Sohn, Suhl
S/237 = Berlin-Luebecker Maschinenfabriken, Werk Luebeck
S243 = Mauser-Werke AG, Werk Borsigwalde, Berlin-Borsigwalde, Eichborndamm
S243G = Mauser-Werke AG, Werk Borsigwalde, Berlin-Borsigwalde, Eichborndamm
27 = Erfurter Maschinenfabrik (ERMA); came under same management as Feinmechanische Werke GmbH
42 = Mauser-Werke AG, Oberndorf a./N, early code
147 = J.P. Sauer & Sohn, Suhl
237 = Berlin-Luebecker Maschinenfabriken, Werk Luebeck
243 = Mauser-Werke AG, Werk Borsigwalde, Berlin-Borsigwalde, Eichborndamm
337 = Gustloff Werke, Werk Weimar, Weimar
660 = Steyr-Daimler Puch, Steyr, Austria
945 = Waffenwerke Bruenn AG, Brno, Czechoslova