| 摘要 |
PURPOSE:To improve the secret securing property of a magnetic medium and, at the same time, to make the recording capacity of the medium controllable in accordance with the number of characters, by making the bit number of optional using data which are written on the magnetic medium optional bit number which can satisfy the quantity of using codes. CONSTITUTION:In a 1st stage, system fixing data which have a fixed bit number with respect to a system are recorded in a 1st area 1 and, in a 2nd stage, optional using data re recorded in a 2nd area 2 with an optional bit number. In a 3rd stage, system fixing data which have a fixed bit number with respect to the system are recorded in a 3rd section is discriminated, the data re not easily decoded since the bit constituting number of the characters of the optional using data section is changed. Thus a secret securing property is improved and the constituting bit number of the optional using data section 2 can be matched to the quantity of required codes.
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