My understanding of the "BOSCH" date codes is it is not a Bosch system per se but a wider DIN system used by a lot of manufacturers in Germany and maybe elsewhere in Europe. One of the first lists of these codes I saw was for Junkers fireplaces !!
It might also be good to start a thread on all the places that date codes exist on components and the form they take. (With photos where possible to make them easier to find / recognise) For example the CDI boxes have a 3 digit code stamped into one of the side panels at the bottom, the fuel pump is stamped like the coil etc. I have been surprised at how many original parts like this are still on / with my car