Disclosed is an optical disk barcode forming method wherein, as information to be barcoded, position information for piracy prevention, which is a form of ID, is coded as a barcode and is recorded by laser trimming on a reflective film in a PCA area of an optical disk. When playing back the thus manufactured...http://www.google.com.tw/patents/US6470452?utm_source=gb-gplus-share專利 US6470452 - OPTICAL DISK, AN OPTICAL DISK BARCODE FORMING METHOD, AN OPTICAL DISK REPRODUCTION APPARATUS, A MARKING FORMING APPARATUS, A METHOD OF FORMING A LASER MARKING ON AN OPTICAL DISK, AND A METHOD OF MANUFACTURING AN OPTICAL DISK