Who is parked?

You answered correctly. According to German traffic rules, a vehicle is considered parked if it is stopped for more than three minutes or if the driver leaves the vehicle, regardless of the time. Simply waiting, even for an extended period at something like a closed railway barrier (such as described in answer 3), is not considered parking—it is considered waiting. Knowing this distinction helps you interpret situations where stopping is allowed and when it counts as parking (which could be restricted in some zones).