Boolean value shown as True/False

       <ColStyle Name="Named" Width="60" Height="0" SortName="Id">

         <CellTemplate ObjectTypeName="user">

           <TextBlock Height="Auto" HorizontalAlignment="Left" Text="{Binding Path=[user.namedLogin]}" />

         </CellTemplate>

       </ColStyle>

Boolean value shown as tick mark or empty

       <ColStyle Name="Named" Width="60" Height="0" SortName="Id">

         <CellTemplate ObjectTypeName="user">

           <TextBlock Height="Auto" Margin="0,0,0,0" HorizontalAlignment="Center"

                       FontWeight="Bold" Text="√"

                        Visibility="{Binding Path=[user.namedLogin], Converter={StaticResource NullValueConverter}, ConverterParameter=Collapsed:Visible}" />

         </CellTemplate>

       </ColStyle>