The Seamless RNCs are served through Esri’s GIS Image Extension product. Chart display order and visibility are determined by Esri algorithms that display the appropriate chart. Chart draw order is determined by the area of the chart, and charts with a smaller area have display order precedence over charts with a larger area. Only official charts from OCS may be used for navigation. The charts in this map service, though derived from official charts, are not to be used for navigation.