Rather than a T-Track counterweight fly system where the weights are perpendicular to the wall, a lattice track (usually used for the fire curtain if full-height flyspace, and sometimes for the main rag with the arbor on the opposite side) has the weights parallel and just a short distance away from the US side of the proscenium wall. See the picture in this post: http://www.controlbooth.com/forums/...re-curtain-lattice-work-fight.html#post270403 .
From http://www.sapsis-rigging.com/glossary.html :
http://www.jrclancy.com/latticetrackarbors.asp
From the above picture, it looks like a regular arbor, but has guide rails or T-track on both long sides.
From http://www.sapsis-rigging.com/glossary.html :
[SIZE=-1]Lattice Track [/SIZE][SIZE=-1]A parallel pair of angles or other structural members that guide an arbor or clew. Low friction slides or roller guides are placed on both sides of the device to be guided. [/SIZE]
http://www.jrclancy.com/latticetrackarbors.asp
From the above picture, it looks like a regular arbor, but has guide rails or T-track on both long sides.