On POSIX platforms such as Unix, Linux and others, locale identifiers are defined in a way similar to the BCP 47 definition of language tags, but the locale variant modifier is defined differently, and the character set is optionally included as a part of the identifier.
Microsoft is starting to introduce managed code application programming interfaces (APIs) for .NET that use this format.
One of the first to be generally released is a function to mitigate issues with internationalized domain names,[4] but more are in Windows Vista Beta 1.
Starting with Windows Vista, new functions[5] that use BCP 47 locale names have been introduced to replace nearly all LCID-based APIs.
A POSIX-like locale name format of language[_country-region[.code-page]] is available in the UCRT (Universal C Run Time) of Windows 10 and 11.