An internationalized application can run in multiple language environments with no change. In each environment, the application localizes—that is, determines what language, character set, and datetime and money formats to use—through the use of external information, such as an external configuration file or environment variable.
Client-Library includes powerful localization mechanisms that make it easy to develop internationalized applications:
The locales file maps locale names to language/character-set/sort-order combinations.
Applications can check the value of environment variables at runtime to determine what locale to use.
Applications can use different locales for different parts of an application. For example, an internationalized sales application that runs in French in France and Italian in Italy might generate reports for the London office using a U.S. English locale.