That is probably so it can't be installed backwards.
I don't see anything else that could be a part number, and this is just a guess, but this manufacturer probably makes these in several sizes, the 127 may be their size/model designation
My german is very rusty but I think the other letters say this side toward ???
edit - a quick google search shows my german is mostly correct according to some Mercedes forums, google "diese seite z gelenkw" is "this side toward driveshaft", spend some time reading the forums & you can probably figure out what it is from