** [https://en.wikipedia.org/wiki/Universal_Product_Code UPC]
* Varmenteet:
** [[X.509]], [[Tekniikka/Varmenne|Varmenne]], [[Viro/Henkilökortti/Varmenne]]
** [https://en.wikipedia.org/wiki/Certification_path_validation_algorithm Certification path validation algorithm]
* Tunnukset