I will try to do some research to determine when and why this three-letter code was required. I believe that it was required in order to import watches into the United States.

I am uncertain when this requirement was in effect. Still, the photos below establish that we see the mark on both the Ed. Heuer and Heuer Leonidas movements.

Who can provide more photos of movements that have these markings? Does anyone have more information about the requirement for these markings? When and why it was in effect?

Of course, we see the "MN" and later "SX" on the other side, below the balance wheel, but that seems to be something entirely different.

Jeff

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: All this talk about movements and their markings made me want to
: snap a couple of shots for "Macro Monday" . . . from a
: Carrera 2447 NS, as shown HERE .

: Anyone else want to show us some macro, some movements, etc.?

: Jeff

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