Abstract: In a system for displaying prices in a retail store, improved system architecture and stored programs are disclosed to permit improved accuracy in confirming the physical location of display devices called labels. A response from a label to the host, or central computer, has appended to it an additional message by an appender, one of a plurality of appenders located throughout the architecture. The appender's message permits localization of the labels. A power-on status flag in a response from the labels permits the central computer to determine, through global inquiries to all the labels, whether any of the labels has had an interruption of power. A dongle or RF-linked bar-code scanner permits store personnel to send messages to the central computer to request that labels in a particular subarea of the store display alternative information such as the amount of inventory for items in that subarea.