ISM wall and column definitions are much more flexible than those in RAM Concept . However, because most building structures have regular features such as vertical columns, this normally won’t be a significant issue.

An ISM repository models an entire building. Support members may extend through all stories of the building and be connected to members on each story. ISM walls are surface members; they may be as complex as slabs, with openings, arbitrary shapes and thickness variations. Walls and columns can also be sloped.

On the other hand, RAM Concept only models vertical support members, and their height is assumed to extend just to the next slab above or below. RAM Concept walls are rectangular and openings are not supported.