A CXF file is a GIS file saved in the Coordinates eXport Format (CXF), developed by HeightMap.org. It contains vector image data in an organized way and can comprise of GIS data or vector graphics, such as drawings.
CXF File Format - More Information
CXF file is saved as plain text file and contains vector map (VMAP) coordinates for representation of geographic locations. Some of the vector map data that a CXF file can include terrain data, topographical information, landmarks, and buildings. CXF files can be exported to several different GIS file formats such as .AI, .XAML, .SVG, .EMF, .KML, and HTML5 formats.