A method for removing andor replacing tubes for generating ions in air flowing through an enclosed or partially enclosed structure. If the authentication device of the visited network cannot determine the home network of the user based on the user identification, then it queries a core platform, which may be outside the first network. This prevents the knobs from squeezing through the holes and thus prevents the strap from disengaging the sole. A data unit output from the upstream operator may be marked to indicate that the data unit has been processed by the upstream operator. A data transmission module has a conductor extending from the compass module to an amplifier and cable for amplifying azimuth data signals and remotely transmitting them.