Abstract: Methods and apparata for electronic labeling and localizing an end point and for determining the distance between an interrogator and the end point. In one embodiment, a system is provided that includes an interrogator that transmits an identification code signal that includes a representation of the identification code of the end point to be localized. The interrogator also receives a tag response signal that is transmitted from a tag associated with the end point. The tag transmits the tag response signal upon receiving the identification code signal and confirming that the identification code signal includes a representation of the identification code. The system also includes a localizer, which is hardware, software, or both, that determines the distance between the end point and the interrogator based on the identification code signal and the tag response signal.