public abstract class Order
{
    public enum OrderCategory
    {
        TICK,
        DESTINATION,
    }
    public enum OrderType
    {
        IDLE,
        MOVE_THRUSTERS, MOVE_WARP,
        ENTER_GALAXY, EXIT_GALAXY,
        ENTER_NEBULA, EXIT_NEBULA,
        ENTER_SYSTEM, EXIT_SYSTEM,
        ORBIT, LEAVE_ORBIT,
        LAND, TAKE_OFF,
    }

    public OrderCategory Category { get; protected set; }
    public OrderType Type { get; protected set; }
}