| 摘要 |
An optical card of write-once type including a rectangular card-like substrate on which a number of tracks (62) are formed in parallel with each other. In each track, one or more data record sectors (65) are provided and at the same time, one or more alternative information record sectors (66) are provided. When data could not be recorded correctly in a desired data sector in a desired track, the same data is recorded again in an alternative data sector. Then, in an alternative information record sector in the desired track, there in recorded alternative information representing an address of the alternative data sector. The alternative information record sector can be made much smaller than the alternative data sector, so that user area can be utilized efficiently as compared with a known optical card in which one or more alternative data sectors are previously provided. Moreover, the alternative information is recorded in a track in which the data could not be recorded correctly, the access time can be shortened materially as compared with a known optical card in which the alternative information is recorded in a directory track.
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