kml2kmz copies all the support documents used by the kml into a single 'files' folder, and updates the file path in the kml to the new relative path accordingly. The kml is also copied, then zipped up with the new copies of supporting files. The zip file is then renamed with a .kmz extension, and put in the same folder as the original kml. The new copies of supporting documents are then deleted by default. Supporting documents referenced by KML attributes are not yet supported.