The tables below list two types of locale codes:

• Website locale codes - for targeting ads at specific languages. These requests take locale codes for AFS or AFC (whichever service the website is set to), in the table below, except where noted.
  Examples:
  AccountService.getWebsiteLocale return value
  AccountService.getSupportedWebsiteLocale return value - returns unfiltered list of locales (from either column)
  AccountService.getSupportedWebsiteLocaleForSyndicationService return value
  
  This locale field accepts the Website locale codes listed for "AFS" in the table below.
  SiteProperties.locale - The language for the search button in AdSenseForSearchService
  
  This locale parameter accepts the Website locale codes listed for "AFC" in the table below.
  
  If a website locale is not supported by AFCe, and if you try to use addSyndicationService to add AFC to an account with that website locale, the request will fail.
• Users preferred codes - a developer's preferred language for the AdWords web interface and for receiving email promotions
  Examples:
  AccountService.setUsersPreferredLocale usersPreferredLocale parameter
  AccountService.getUsersPreferredLocale return value
  display_locale request header

The services accept a subset of ISO-639 two letter language codes, where a few of the codes (such as zh_CN) contain locale-specific codes. Such locale-specific codes can use either an underline (zh_CN) or hyphen (zh-CN) separator.