Сравнение строк в C#: разница между CurrentCultureIgnoreCase и InvariantCultureIgnoreCase

Microsoft дает достойное руководство, когда использовать свойство InvariantCulture:

MSDN: свойство CultureInfo.InvariantCulture

... an application should use the invariant culture only for processes that require culture-independent results, such as formatting and parsing data that is persisted to a file. In other cases, it produces results that might be linguistically incorrect or culturally inappropriate.

Security Considerations

If a security decision will be made based on the result of a string comparison or case change, your application should use an ordinal comparison that ignores case instead of using InvariantCulture. [...]

String Operations

If your application needs to perform a culture-sensitive string operation that is not affected by the value of CurrentCulture, it should use a method that accepts a CultureInfo parameter. [...]

Persisting Data

The InvariantCulture property is useful for storing data that will not be displayed directly to users. Storing data in a culture-independent format guarantees a known format that does not change. When users from different cultures access the data, it can be formatted appropriately based on specific user. [...]

В других сообщениях есть хорошие советы, но я подумал, что было бы неплохо показать пример того, где это определенно имеет значение:

using System;
using System.Globalization;
using System.Threading;

class Test
{
    static void Main()
    {
        CultureInfo turkish = CultureInfo.CreateSpecificCulture("tr");
        Thread.CurrentThread.CurrentCulture = turkish;                

        // In Turkey, "i" does odd things
        string lower = "i";
        string upper = "I";

        Console.WriteLine(lower.Equals(upper, 
            StringComparison.CurrentCultureIgnoreCase));
        Console.WriteLine(lower.Equals(upper, 
            StringComparison.InvariantCultureIgnoreCase));
    }
}

(Несомненно, много других случаев - это был только первый, о котором я подумал.)