Abstract: An electronic chart system in which charts of the earth are stored in digital representation and communicated to the operator by a visual display. Through the use of a Loran-C receiver or the like, the system additionally plots the carrier's position on the visual representation of the chart. The visual display is a cathode ray tube on which the visual representation is compressed or expanded to meet the demands of the operator so that the appropriate resolution is thereby obtained. To minimize memory size an encoding format is used which provides a data word for indicating the first physical element of the run line, a data word for the number of runs per line and data words for the lengths of N-1 runs of up to two variables for each line of the chart.