Abstract: Interconnection module for connection to other interconnection modules to provide a back plane of any desired size and configuration in electronic data shelf arrangements. The module has optical terminals extending from a front face for signal transmission and reception relationship terminals, preferably optical terminals, for signal interconnection with at lest one other interconnection module. Signal conductors extend from the terminals of the front face to the terminals of the other face. Flat cables are conveniently used to interconnect modules which may be relatively positioned horizontally or vertically spaced or both.