According to the invention, within a searching space {HEAD ~ 600 all traces} of {TAIL ~ the clients} 200, 300, 400 can be localized with additional information, for example, the content space 602 
of
According to the invention , within a searching space { HEAD ~ 600 all traces } of { TAIL ~ the clients } 200 , 300 , 400 can be localized with additional information , for example , the content space 602
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH