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Shoppers will soon be able to tell how much they’ve spent by checking their
credit card. JVC of Japan and Nexxt Media of Singapore have developed a
credit-card-sized sliver of CD material which has read-only and write-once
sections. The read-only section keeps a permanent record of ID and account
information, while the rest of the disc is coated with a dye that changes colour
in laser light to record user data, such as spending. The data can be encrypted
for security, and is read and recorded in the tray of a PC’s standard CD
recorder.