WPF numeric format

WPF numeric format

I have this XAML for acolumn into DataGrid
<DataGridTemplateColumn Header="% Deduccion Anticipo">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding NumPorcentajeAnticipo, Mode=TwoWay,
StringFormat={}{0:00.}%}" Visibility="{Binding
Merlin_ConceptosFacturacion.BitOtrosItms_Anticipos,Converter={StaticResource
boolToVisibility}}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<TextBox Text="{Binding NumPorcentajeAnticipo,
Mode=TwoWay,StringFormat={}{0:00.}%}" Visibility="{Binding
Merlin_ConceptosFacturacion.BitOtrosItms_Anticipos,Converter={StaticResource
boolToVisibility}}"/>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
The Stringformat applys as i expect, but muy problem is the user can fill
it with any char alpha, number symbol, how can i do to prevent it, it is
posible set an inputmask ?
I'm was trying with another StringFormats but any one of them work as I
expect.