A promotional version of Michael Jackson's new single has been designed so it cannot be played on a CD-Rom drive.
The special CD, distributed in the UK, should prevent the music being pirated on the internet before its official release.
The discs for You Rock My Worldfeature a system called key2audio that allows use on a CD player but causes a CD-Rom drive to misread the data.
Key2audio also makes the audio CD incompatible with CD-R and CD-RW drives.
It places false instructions in an area of the CD that software developers use to help with error corrections.
A Sony spokesman told New Scientistmagazine: "There are no plans currently to use similar technology on commercial releases of this record".
But some industry analysts believe it could be used in the future - preventing even legitimate copying for personal use.
PA
