I have this on my number plate (at the edge) it just means registered in Europe (UK in my case) Have had the car from new & it came from the dealership with this on the usual plate.
There's an 'EUR' number plate country code, but it's for use on EU official vehicles. There are also loads of unofficial country-type codes on car registration plates, such as 'ENG' for England. I expect that's what you've seen. See here for examples...