current in the tag 19 causing it to communicate its stored information which will be described in more detail below the rfid tags 19 contain generally simple information but the tag information may be as widely varied as the uses for the system 100 itself for example tags can contain simple presence no presence bit or detailed information regarding an entire build process or specifications about lot number serial number and the like the radio frequency of the interrogator powers up the tag and the carrier frequency usually 125 khz for passive tags in one embodiment becomes the clocking frequency to generate a clock to clock the data out passive tags can be made and used very inexpensively making them more economical for use with multiple read locations in one arrangement shown in fig3 interrogator 104 is operatively connected to a plurality of sensing antenna circuits 110 on a nesting station 112 via connection lines 114 in this arrangement two quad nesting stations are shown in another arrangement interrogator 106 is operatively connected to a plurality of sensing antenna circuits 116 on quad nesting station 118 via connection line 120 and to antennas 122 of dual nesting station 124 via.