Other locale representations

Many environments, such as C++, Java, .NET Framework, Python, XML, and other Unicode-based environments use a common format for specifying a locale. This format is specified in the IETF BCP 47 standard. For more information about the BCP 47 format, refer to Standard locale names.

Windows APIs have used BCP 47 locale names since Windows Vista. There are other locale representations, however; some of which are discussed below.


Before Windows adopted IETF BCP 47 locale names, the [MS-LCID]: Windows Language Code Identifier (LCID) Reference was used to specify locales for Windows. LCIDs are also known as culture identifiers in the Microsoft .NET Framework environment.

Note that LCIDs are being deprecated, and implementers are strongly encouraged to use newer versions of APIs that support BCP 47 locale names instead. Each LCID can be represented by a BCP 47 locale name, but the reverse is not true. The LCID range is restricted and unable to uniquely identify all the possible combinations of language and region.

LCID examples

LCIDs can identify neutral locales (a language without any region-specific information), specific locales (a language with a regional variant), and locales with alternate sort (for languages that have multiple methods of sorting data).

LCID Language tag Type
0x00000075 haw Neutral locale
0x00000409 en-US Specific locale
0x00010407 de-DE_phoneb Alternate sort for locale


The POSIX locale format, used on Unix, Linux, and other systems, is defined by ISO/IEC 15897:2011 and uses this format: [language[_territory][.codeset][@modifier]]

The component parts are as follows:

  • language is a two-letter language code from ISO 639
  • _territory is a two-letter country/region/subdivision code from ISO 3166
  • .codeset is any pre-defined name for a character set or encoding identifier (for example, iso885915 or UTF-8)
  • @modifier specifies an adjustment to the default locale behavior such as date/time/currency formatting or sorting method

The language code is the only mandatory part of a POSIX locale. Including a territory code is very common, as many languages are used in different countries/regions with regional variations.

The modifier part is not specified in any unified way. One common example is @euro. It was added to certain locales in the early 2000s when some countries/regions in the European Union changed their currencies to the Euro.

POSIX example

The POSIX locale de_DE.UTF-8@euro consists of the following parts:

  • de for the German language
  • _DE for Germany
  • .UTF-8 for the character encoding
  • @euro to indicate that the locale is now using the Euro currency

Comparative locale IDs

Here are some sample locales using the representations discussed above. Note that BCP 47 locales use a hyphen (-) to separate the language and territory codes, while POSIX compliant locales use an underscore (_).

BCP 47 LCID POSIX compliant Description
de-DE 1031 de_DE German for Germany
es-ES-u-co-trad 1034 es_ES@traditional Spanish for Spain, specifying the traditional sort order
sr-Latn-CS 2074 sr_RS.UTF-8@latin Serbian for Serbia, using the Latin script and the UTF-8 encoding