True wood frame construction is distinct from earthfast construction. In earthfast construction the main columns and possibly other elements, such as palisading, are partially buried in the ground and gain rigidity from this. A frame, by contrast, is braced, and even if some elements happen to enter the ground this is not the main source of its stability. The box frame, in particular, is like a box in that it could, in principle, be picked up and moved without collapsing. Therefore, it may rest upon the ground, upon a masonry plinth, or upon stumps or piles. The topics that follow relate principally to true frame construction, although earthfast construction is also referenced. Buildings whose principal structure is of steel or other framing, or whose external walls are of load-bearing masonry are not considered in this article, although many of the same references will apply.