A type of electronic navigational chart (ENC) format.
The United Kingdom Hydrographic Office (UKHO) publishes the digital raster charts in Hydrographic Chart Raster Format (HCRF). These raster charts are scanned from traditional paper charts and are realized as a set of one or more panels. The chart itself is always the panel 0 and each inset plan represents an additional panel. Some panels may even be split into sub-panels because of mathematical problem encountered by the dateline or the coverage of a wide latitude range. Following the notices to mariners for paper charts the UKHO publishes weekly updates, which can be applied to the ARCS chart.