GRAMET contains a model for icing.
The German Weather Service (DWD) ADVICE model is rubbish in my experience. It forecasts icing always and everywhere, a perfect example of the CYA (cover your ...) policy. Make sure there can never be icing where it was not forecast because you can get in trouble for not forecasting it but you won't for forecasting icing which is not going to be there. Makes the actual charts useless for flight planning.
Is the concept of "flight into known icing" versus some specific weather service enforced in Germany?
It would be mad to do that, because a pilot can legally brief from so many weather sources.
When the FAA tried that approach, briefly, some years ago, they stopped it pretty fast because it didn't make any sense.
In the UK we have the infamous Form 215, which every PPL is taught to worship, and which forecasts icing conditions in all IMC regardless of temperature.
Speaking of reality, I cannot see how icing (i.e. supercooled water droplets) can be forecast. Maybe they can be, but by far the worst icing incident I ever had was in a very innocent looking stratus layer, 1500ft base, 4000ft tops. 30mm of ice in 5-10mins.
Icing (or the lack of it when it "should" be happening) is so random that I cannot see any "icing" forecast having any meaning for flight planning purposes - unless you make it totally banal and forecast icing everywhere there are fronts, with a disclaimer that it could also be everywhere else, which would be probably about right 
