When it is desired to eliminate the Jth input line (e.g. because the data arriving on the Jth input line is defective) the fuse in the Jth selection circuit is blown (e.g. by a laser, by high-amperage current or other well known means) all of the upstream selection circuits (if any) (i.e. the M through (J+1)th selection circuits) will continue to provide signals from the first input to the output