Well, about my question, i think i understood from the help menu that the values of Area Type are a hard coded set of rules. I thought that were just simple text values. Now it seems if I want to specify an "area type" that is defined in the national standard and witch i want it to show in my language in the area tag (like a translated Gross Building Area) i have to do a text parameter.

And about the rules i think if the rules fit in one of the predefined rules from the Area Type parameter i can use the automatic settings, and if not, i will use sketch mode.

Ah, and the rules are here:

A related observation too.

The area is calculated by using the perimeter at the Computation Height parameter. In revit 2011 this setting was by default 4' or 1200mm above the level. It was a type parameter of the level system family. Now in 2012 is an instance parameter and is by default set to zero. So don`t forget to adjust in sections by selecting levels) all the instance Height Computation parameters if you think the zero value is not an appropriate value. In the wiki help for 2012 they have the explanation that is the same as 2011. I think they forgot to update.