Abstract: An information system for a shelving system, such as in a supermarket, is disclosed. The system comprises a central data transmission source, a data distribution network, a common data link, and display units. The display units are capacitively coupled to conductive elements of the common data link.

Abstract: A method of transmitting a series of data elements by means of a series of discrete signal pulses separated by intervals, wherein the data elements are of a number of discrete types and are each represented by a respective interval between successive signal pulses, and wherein a number of further intervals, each different from the intervals assigned to data elements and different from the sums of or differences between any two data element intervals, is defined wherein each of the further intervals represents a change in the series of data elements from one element type to another, the number of further intervals being less than the number of different data element types.