You are only allowed to use it in "raw data mode" i.e. showing either Lat and Long or a range and bearing from a waypoint. Moving map displays and GoTo features are not allowed.
Oh well, it's so reassuring to know the JAA training is bang up to date. An IFR pilot, single pilot IFR, is really going to love the lat/long coordinate option. Wonderful stuff - and a great safety enhancement, plugging in lat/long coordinates.
A £50 camping-shop GPS will give you lat/long and a waypoint relative bearing - almost totally useless for aviation.