<cc:XmlDropDownList ID="XmlDropDownList1" runat="server"
DataSourceID="XmlDataSource1"
DataTextField="name"
DataValueField="id"
AppendDataBoundItems="True"
HierarchicalValueModes="DataValueField">
<asp:ListItem Text="= Select Operating System =" Value="" />
</cc:XmlDropDownList>
<asp:RequiredFieldValidator runat="server" ID="rfvDropDown" ControlToValidate="XmlDropDownList1"
Display="Dynamic" Text="***" />
<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/App_Data/Sample.xml"/>