@User: The only problem with that approach is that I have been thinking about that the area in liberty is not strictly about area but about preferrance of one cell over the other cells, and just putting the area into that field might not be the right target goal, perhaps power, timing, or some other characteristic might also be relevant and be useful to be used in that field to optimize for the target application? Well, if anyone wants to put something else into that field, he can do that, but I think it would be worth it to have a recommendation which unit to use for the field if only area optimisation is the goal.