a recording - tape - reel assembly , such as used with a computer , has an electronic tag to enable the presence of the assembly to be detected in a presence detection system in order to inhibit the unauthorized removal of the assembly from premises equipped with such a system . the assembly includes a reel for holding a recording tape , an electronic tag for enabling detection of the presence of the assembly in a presence detection system , and a housing that isolates the electronic tag from the recording tape and makes the tag inaccessible to users of the assembly . electronic tags are housed in both reels and cassettes that contain reels .