In {HEAD ~ the at least one indication writing portion}, regions made of magnetic material spaced by magnetically blank portions are provided so as to define a code which can be detected by {TAIL ~ a magnetic reading head} 
In { HEAD ~ the at least one indication writing portion } , regions made of magnetic material spaced by magnetically blank portions are provided so as to define a code which can be detected by { TAIL ~ a magnetic reading head }
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL