Validation for enter key and double quot

Validation for enter key and double quot;

FilteredTextBoxExtender3.ValidChars = FilteredTextBoxExtender3.ValidChars + "\r\n";

<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender3" runat="server"
                                FilterType="Custom, Numbers, UppercaseLetters, LowercaseLetters" ValidChars=" !@#$%&(),./= +&quot;"  TargetControlID="txtMessage"> </cc1:FilteredTextBoxExtender>