Yeah it is the product code checked to update the firmwares, not only symbian but all nokia phone I think, at least with my N900. Mine is coded for Hongkong N900 version. Been thinking if I should change the code to EU or US though. Can anyone tell the difference between HongKong N900 PR1.3 and EU N900 one beside chiness input support (which I don't use)?

I reflashed the phone to PR1.3 with the global image because I could not get the OTA update, but infact the global image is a little bit different from the Hongkong firmware (no chinese input). After reflashing the global image, I have to run Nokia Software Updater to flash to the HongKong PR1.3. I don't know if I should do that or it is just a waste of time.

My N900 is not operator locked, so I do not have to worry about changing IMEI though. I don't think my carrier will help me lock the IMEI even if the phone is lost. They will laugh at my stupidity for not buying a properly protected local phone, maybe.