Often overlooked is the role played in the publishers supply chain by that less glamorous cousin to the ISBN, the SAN (Standard Address Number). SAN was initially developed at R.R. Bowker in response to retailers’ requests for a standardized account to facilitate ordering across the supply chain and became a standard (ANSI/NISO Z39.43) in 1980. This article describes what a SAN is, how it is used, and the benefits it provides to trading partners in the industry.