zzz in .net DateTime ToString formatter

gistfile1.txt

{
    var utcEpoch = DateTime.Parse("1970-01-01", CultureInfo.InvariantCulture,
                                    DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal);
    Console.WriteLine(utcEpoch.Kind);
    Console.WriteLine(utcEpoch.ToString("o"));
    Console.WriteLine(utcEpoch.ToString("zzz"));
}
Console.WriteLine("-----------");
{
    var utcEpoch = DateTime.Parse("1970-01-01", CultureInfo.InvariantCulture,
                                    DateTimeStyles.AssumeUniversal);
    Console.WriteLine(utcEpoch.Kind);
    Console.WriteLine(utcEpoch.ToString("o"));
    Console.WriteLine(utcEpoch.ToString("zzz"));
}

Output:
Utc
1970-01-01T00:00:00.0000000Z
-06:00
-----------

Local
1969-12-31T18:00:00.0000000-06:00
-06:00

Don't forget about DateTimeOffset. It provides an epoch time