| 摘要 |
A data reader is arranged to read data comprising user data 30 and non-user data 32, 34 written across at least two channels of a data-holding medium 10 , said data being arranged into a plurality of data items 26 each containing user data and non-user data, with said non-user data holding information relating to said user data, including write pass number information, and data items written across the said channels at the same time being identified as a set of data items, said data reader holding a current write pass number and having a read head 12 for reading a respective said channel of said data-holding medium 10 to generate a data signal comprising said data items, and processing circuitry 258, 280 arranged to receive and process said data signals of a set of data items, including processing said write pass number information of each of said data items in said set, and causing updating of said current write pass number held by said data reader on the basis of the write pass number information of said data items in said set.
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