An external reference is an identifier for a system object, such as a location. This identifier, or code, can be used to refer to a system object, such as a location when using web services, file imports, and other methods of sending data to the SBLP from an external source. For example, assigning descriptors to locations using a Location Descriptor File requires the locations to have external references.
External references are typically not required, but in a database that is dependent on external data feeds and analysis, it is considered "best practice" to always set external references for items. Almost all external references are limited to 20 characters, with the exception of transaction external reference which has a maximum length of 40.
An example external reference for a location named "Smith's Restaurant" might be, SMRST.