I read the question on the IRC yesterday from Alan about how to format dates in rowfilters.

This is what I found in our existing code:
in csharp\ICT\Petra\Server\lib\MFinance\Common\Common.Tools.ExchangeRates.cs:
rates.DefaultView.RowFilter = ADailyExchangeRateTable.GetDateEffectiveFromDBName() + "<= #" +
ADateEffective.ToString("yyyy-MM-dd") + "#";

That should work in every culture.

Thank you Timo. I did not know that was there in Common.Tools.ExchangeRates.cs. I did have the same thing in my screen, but I did not have the same method everywhere. I was getting errors when I set my PC regional settings to German(Germany). I carried on yesterday evening and ended up using this everywhere in my code and it seems fine....

RowFilter = String.Format(CultureInfo.InvariantCulture, "{0}='{1}' and {2}='{3}' and {4}<#{5}#",

followed by the necessary parameters and where {5} (in this case) is the DateTime object itself (not a string representation of it).

This seems also to work everywhere. Let me know if you see any potential problems