Devices and methods for spinal fixation employ at least first and second plates that are configured to allow progressive sliding advancement of the plate members toward one another and limit movement of the plate members away from one another after installation. Methods for guiding and depositing flat products, in particular print carriers, in duplicating machines are also provided. In navigation mode, a direction input selects the next interactive element in the direction indicated. , those complying with Maxicode and DataMatrix standards, as well as stacked linear bar codes, e. Power consumption is reduced by reducing the amplification used under typical conditions.