Parker pen code for 2012

[tarjeipark]

I bought a beautiful and smooth writing brand new Parker Duofold Centennial (made in France). The pen has an engraved Parker pen date code of '1A', which denotes the 3rd quarter of 1992. If it is 2012, it would be 'A.1'. Why '1A' ?

[auto winder]

I found some explanation at http://parkerpens.net/codekey.html , it seems they change the system a little bit every 10 years to avoid ambiguity.