i'm fred clark i'm the senior design principle of the architect for the transit center. and i'm very, very happy to be presenting to you the work we've done on say external wall of the building. i will go through a number of impacts through the work. here you see the outline eased we'll see the choices of how one might pattern this wall. we'll look at the subtilties and we'll look at maintenance and fire safety. we'll go incited business deck and look at the wall from the internal and finally at latin-american and finally at cost. i will say this is as bob mentioned a few minutes ago. this is one of those buildings it's large it has about half a dozen well centers. it's not the biggest but the most visible and the most to maintain the quality and refinement. that really underlay our work to a great deal of time. as i mentioned to you before that about or - it responds to the outside super structure and the skin is a floating network. it increase relates to the design of the structure itself. that's been one of the proposals since the time of competition. that secondary s