Hi Stewart,

Thanks for your help.

: Mick,
: I do have makings on the caseback of my 11630 GMT, same size as
: yours, but not quite like yours. Mine is 'C' followed by 3
: numbers (I forget what they are).
: This signifies that it was made for the Swiss domestic market and
: distributed by Heuer’s Swiss distributors Cuanillon. Hence the
: 'C'.

I know the Cuanillon markings.

: Maybe yours are codes for another country?

In this case it ought to be a rather small market, I did never see similar engravings on other Heuer watches.

The NN-N format lets me think of week-of-the-year and day-of-the-week or total number of a set and ordinal number. Any further ideas?

Cheers,

Mick