| 摘要 |
In an optically readable information carrier, an information symbol has a predetermined area and includes an optically readable mark. The optically readable mark indicates at least part of the predetermined area. The information symbol is optically readable by an information reader after the predetermined area has been identified thereby. A mask member is arranged to abut on the information symbol. The mask member is also arranged to mask at least part of the optically readable mark while keeping presence of the information symbol externally visible to change the predetermined area of the information symbol to be unidentifiable.
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