Barcode

条形码 (Barcode) is a machine-readable symbol that encodes data using a combination of bars, spaces, and characters. Physical music products commonly feature UPC-A or EAN-13 barcodes, which encode numbers belonging to the GS1 Global Trade Item Number system and are used for retail scanning, ordering, and inventory management. In everyday usage, both the barcode pattern and the numbers below it are often referred to as “barcodes,” but strictly speaking, 条形码 is the data carrier, while the GTIN is the encoded product identifier.

UPC-A typically displays 12 digits, while EAN-13 displays 13; in the context of GTIN, they can be represented as a uniform length by padding with zeros or other methods. The final check digit is calculated from the preceding digits according to a specified algorithm and is used to detect common scanning or data entry errors; it is not an encrypted signature verifying the product’s authenticity. White quiet zones must also be reserved on both sides of the barcode, as printing scale, color contrast, and surface reflectivity can affect scanning. A GTIN is typically assigned to a single tradable item. Different numbers may be used for the same album if changes occur in the medium, packaging, number of discs, regional sales units, or versions that require differentiation within the supply chain; multi-disc sets and their individual discs may also have their own identifiers. Historical data in the music industry is not always strictly consistent; early products, promotional discs, and small-scale releases may lack 条形码, and later reissues may reuse or overwrite old numbers.

条形码 does not identify a single physical copy; scanning items from the same batch will yield the same GTIN. To distinguish individual products, a separate serial number, lot code, or two-dimensional data carrier is required. 条形码 is also distinct from the record label catalog number and the recording’s ISRC: it is intended for commercial transactions, whereas the catalog number pertains to the distributor’s catalog and the ISRC pertains to the recording.

The 条形码 on packaging may be printed, labeled, or added later by a distributor. When a sticker covers the original code, the two numbers may correspond to the original regional product and the repackaged sales item, respectively; the number alone cannot determine who added the sticker. Databases typically store readable numeric values rather than just images, and retain leading zeros, as removing leading zeros would alter the standard representation.