Oval plate numbers on plein airs
I am trying to sort out the numbers on the oval plate on R4's. It usually has three numbers, the top one refers to the type of R4, e.g. for my original Sinpar Plein Air the number is R1123, the number in the middle refers to a country or region specific series, e.g. 100 for France, 120 for Germany and 250 for North America. The bottom number, I believe, is the production number of the type specified on the plate, on my Plein Air this is 690863, which suggests that it is the 690863th R1123 (That seems a lot). Is this correct and what is the country series number for UK. Is it 300?