asp.net extension GridView adds the code for the radio button column

/// <summary> 
///  Radio button column  
/// </summary> 
/// <remarks> 
///  If it's not set GroupName , use the GridView the ID As a GroupName 
///  If it's not set DataField , use the RowIndex As a Value 
///  Allows setting DataFormatString Formatted data  
/// </remarks> 
[AspNetHostingPermission(SecurityAction.Demand, 
Level = AspNetHostingPermissionLevel.Minimal)] 
public class RadioButtonSelectField : DataControlField 
{ 
/// <summary> 
///  Radio button group name, go by default GridView the ClientID 
/// </summary> 
[Description(" Radio button group name, go by default GridView the ClientID")] 
public string RadioButtonGroupName 
{ 
get 
{ 
return this.ViewState["RadioButtonGroupName"] as string; 
} 
set 
{ 
this.ViewState["RadioButtonGroupName"] = value; 
} 
} 

/// <summary> 
///  Radio button style  
/// </summary> 
[Description(" Radio button style ")] 
public string RadioButtonCssClass 
{ 
get 
{ 
return this.ViewState["RadioButtonCssClass"] as string; 
} 
set 
{ 
this.ViewState["RadioButtonCssClass"] = value; 
} 
} 

/// <summary> 
///  The data expression to bind  
/// </summary> 
[Description(" The data expression to bind ")] 
public string DataField 
{ 
get 
{ 
return this.ViewState["DataField"] as string; 
} 
set 
{ 
this.ViewState["DataField"] = value; 
} 
} 

/// <summary> 
///  The data expression format to bind to  
/// </summary> 
[Description(" The data expression format to bind to ")] 
public string DataFormatString 
{ 
get 
{ 
return this.ViewState["DataFormatString"] as string; 
} 
set 
{ 
this.ViewState["DataFormatString"] = value; 
} 
} 

/// <summary> 
/// return self; 
/// </summary> 
/// <returns></returns> 
protected override DataControlField CreateField() 
{ 
return this; 
} 

/// <summary> 
///  Add controls  
/// </summary> 
/// <param name="cell"></param> 
/// <param name="cellType"></param> 
/// <param name="rowState"></param> 
/// <param name="rowIndex"></param> 
public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex) 
{ 
base.InitializeCell(cell, cellType, rowState, rowIndex); 

if (cellType == DataControlCellType.DataCell) 
{ 
var literal = new Literal(); 

if (string.IsNullOrEmpty(this.DataField)) 
{ 
SetLiteralHtml(literal, rowIndex.ToString()); 
} 
else 
{ 
literal.DataBinding += new EventHandler(literal_DataBinding); 
} 

cell.Controls.Add(literal); 
} 
} 

void literal_DataBinding(object sender, EventArgs e) 
{ 
if (string.IsNullOrEmpty(this.DataField)) 
{ 
return; 
} 

var literal = sender as Literal; 
if (literal == null) 
{ 
return; 
} 
var cell = literal.Parent as TableCell; 
if (cell == null) 
{ 
return; 
} 
var container = literal.NamingContainer; 
if (container == null) 
{ 
return; 
} 
bool foundDataItem; 
var dataItem = DataBinder.GetDataItem(container, out foundDataItem); 
if (!foundDataItem) 
{ 
return; 
} 

var dataValue = null as string; 
if (this.DataField.Contains('.')) 
{ 
dataValue = DataBinder.Eval(dataItem, this.DataField, this.DataFormatString); 
} 
else 
{ 
dataValue = DataBinder.GetPropertyValue(dataItem, this.DataField, this.DataFormatString); 
} 

SetLiteralHtml(literal, dataValue); 
} 

private void SetLiteralHtml(Literal literal, string dataValue) 
{ 
var groupName = this.RadioButtonGroupName; 
if (string.IsNullOrEmpty(groupName)) 
{ 
groupName = literal.Parent.Parent.Parent.Parent.ID; 
} 
var cssClass = this.RadioButtonCssClass; 
if (!string.IsNullOrEmpty(cssClass)) 
{ 
cssClass = string.Format("class=\"{0}\"", this.RadioButtonCssClass); 
} 

var selected = false; 
var selectedValue = literal.Page.Request[groupName]; 
if (string.IsNullOrEmpty(selectedValue) == false) 
{ 
if (string.Compare(selectedValue, dataValue, true) == 0) 
{ 
selected = true; 
} 
} 

var rbHtml = string.Format("<input type=\"radio\" name=\"{0}\" value=\"{1}\" {2} {3} />", 
groupName, 
dataValue, 
cssClass, 
selected ? "checked" : string.Empty); 

literal.Text = rbHtml; 
} 
}