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