[mrerick]

The concept of concealment permeated the German thinking as they realized that they had to dodge the inspectors for the IMKK (Versailles Treaty Inter Military Control Commission).... While the police pistols were authorized for Simson manufacture and rework (and were being unit marked) in the Weimar era, other activities at the arms factories were not permitted.

There is documentation of one of these dodges of inspectors in Mauser during that period. They were not permitted to make "military" caliber pistols for commercial sale, so they designated their C-96 pistols as being "C-96 Pistol model .30 Mauser" in the books which were audited by IMKK staff in Berlin. The actual pistols were "C-96 Pistol model .30 Mauser with 9mm barrel" as found in factory records and being manufactured in Oberndorf. I expect that when IMKK inspectors showed up in Oberndorf, those "special" orders were set aside somewhere.

By 1934, after the Nazi government had decided to ignore the IMKK and Versailles Treaty restrictions, concealment codes really came into use. First was the "K" in 1934 and "G" in 1935 for date codes, and the use of "S" as part of the manufacturer concealment "S/42" to imply some relationship with SImson - the IMKK authorized manufacturer of pistols under the Versailles Treaty. I suspect handguns and specifically controlled items were the early products to get concealment codes, which eventually spread widely in their contracting.

You can see that by then, unit markings had been abandoned for several years with security and concealment of the movement of military units (and eventually the formation and migration of police agencies) a reasonable motivation.