Материал из .Net Framework эксперт
Using the FilteredTextBox Control
<%@ Page Language="C#" %>
<%@ Register TagPrefix="ajax" Namespace="AjaxControlToolkit"
Assembly="AjaxControlToolkit" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Show Filtered TextBox</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:Label
id="lblNumeric"
Text="Enter a Number:"
AssociatedControlID="txtNumeric"
Runat="server" />
<br />
<asp:TextBox
id="txtNumeric"
Runat="server" />
<ajax:FilteredTextBoxExtender
id="fte1"
TargetControlID="txtNumeric"
FilterType="Numbers"
Runat="server" />
<br /><br />
<asp:Label
id="lblProductCode"
Text="Enter a Product Code:"
AssociatedControlID="txtProductCode"
Runat="server" />
<br />
<asp:TextBox
id="txtProductCode"
Runat="server" />
<ajax:FilteredTextBoxExtender
id="fte2"
TargetControlID="txtProductCode"
FilterType="LowercaseLetters,Custom"
FilterMode="ValidChars"
ValidChars="_!"
Runat="server" />
<br />
(A product code can contain only lower-case characters,
underscores, exclamation marks, and no spaces)
</div>
</form>
</body>
</html>