Terrain . . Auto Calculate??

[Tundara Homes]

Okay, I think I just figured out where this bases off of. 11 7/8 floor, plus 1.5 sill plus 6 inch drop from sill. . . I am sure this is documented somewhere, but it just dawned on me today.

The house shown auto calculated my terrain perimeter at 20 1/8". Beautiful. Welcome home hon, the house sank. Why wouldn't chief base an auto terrain off of . . . say .. . garage floor height?? That "usually" is the lowest floor isn't it? Just wondering. Maybe I should add this to suggestions. Maybe nobody cares cause no matter where they chose to put it we'd have to adjust it. Oh bother. . . I am going back to work.....