#P45 document serial number serial numbers

These depend on applying mathematically rigorous serial numbers and serial number arithmetic

The International Standard Serial Number or ISSN seen on magazines and other periodicals, an equivalent to the International Standard Book Number (ISBN) applied to books, is serially assigned but takes its name from the library science use of serial to mean a periodical.Д¬ertificates and Certificate Authorities (CA) are necessary for widespread use of cryptography. Serial numbers also help track down counterfeit currency, because in some countries, each banknote has a unique serial number. These numbers are verified using a certain algorithm to avoid usage of counterfeit keys. Many computer programs come with serial numbers, often called 'Compact Disc keys', and the installers often require the user to enter a valid serial number to continue. Serial numbers are also used as a deterrent against theft and counterfeit products in that serial numbers can be recorded, and stolen or otherwise irregular goods can be identified. Serial numbers are valuable in quality control, as once a defect is found in the production of a particular batch of product, the serial number will quickly identify which units are affected. For more details on this topic, see Numbering scheme.