A string defining the WebUI version. This version string must match exactly what the CPE returns or an upgrade of the WebUI file will be initiated. This only applies to certain CPE types. The CO device will not restrict setting this for CPEs that do not support it, but doing so will likely cause problems. If this field is left blank, but requiredCpeWebUIFilename is set, the CPE will be told to download a new WebUI file whenever it is also told to download a new software image file. This allows the WebUI file to be tied directly to the software image version.