Notes about the 004 file extension:
To open this file type, a required software must be installed. Without it you only see a Windows message "The following file cannot be opened
" (Windows 7) or "How do you want to open this file?
" (Windows 10) if you double-click the file. There click on "More apps"
and choose a suitable software to view such files on your PC or from email attachments.
The 004 file type is primarily associated with 'International S-57 Hydrographic Data' by US NOAA / US Army Corps of Engineers. A vector-based digital file containing marine features suitable for marine navigation. The file is based on the International Hydrographic Organization (IHO) S-57 standard. The file extension, ".000," for a base NOAA ENC cell is used for updating. The first update for a cell will be ".001" the next ".002" and so forth. The file extension .031 is used for catalog data (metadata) relating to the chart data.