Invariant Culture ToUpper, ToLower - C#

Problem

What are ToLowerInvariant and related methods for? You want to read a basic discussion about the method and ToUpperInvariant. Words like Invariant are confusing, as is MSDN.

Solution: ToLowerInvariant usage in C#

When programming recently, I encountered ToLowerInvariant and needed to look up information on it. Also, I wanted to know if it was more efficient than the regular ToLower. What's the point of these methods?

What Microsoft says. MSDN states that ToLowerInvariant and ToUpperInvariant are useful only for operating system "identifiers" and only affect behavior with specific locales, such as Turkish.

• MSDN documentation says.
  If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant methods.
• Links to MSDN.
  Look at the documents--linked in the table below--about ToLowerInvariant, its sister method ToUpperInvariant, and the version that works on the char data type.

Question: what does it mean for most developers?

Absolutely nothing. The usefulness of these methods is very narrow and they are basically irrelevant to many developers. The documents indicate that these methods will only change behavior with Turkish cultures. Also, on Windows systems, the file system is case-insensitive, which further limits its use.

Conclusion: ToLowerInvariant and related methods in C#

These 'invariant' methods are completely irrelevant to my work as a developer. They have an extremely narrow use with Turkish localizations when you need to uppercase or lowercase a file name.

Not only this, but Windows file systems file handling are case-insensitive, making these methods unlikely to be useful even on a Turkish-localized PC.