ISSN

Serial publications are identified at the point of sale by an ISSN barcode, an EAN-13 carrying the 977 prefix assigned to serials. Seven significant digits of the International Standard Serial Number follow the prefix, with two positions reserved for a price or sequence variant and a final Mod 10 check digit. The ISSN International Centre allocates the underlying numbers, which distinguish titles rather than individual issues; an EAN-2 supplement is added when issue-level identification is required. Dimensionally the symbol is an EAN-13 in every respect, including the 0.264 mm X-dimension, the 22.85 mm bar height, and the eleven- and seven-module quiet zones. The encoding is numeric only, and the resulting number behaves as a GTIN-13 for distributors, libraries, and retailers.