e.Item.ItemType

下面是我在repeater里面找panel控件的代码，who帮忙解释下为什么要判断当前点击的项啊，这和找控件有什么关系啊？
 protected void Repeater1_ItemCommand1(object source, RepeaterCommandEventArgs e)
{
  
                if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
                {
                    Panel pan1 = (Panel)e.Item.FindControl("Panel1");
                    if (pan1.Visible == false)
                    {
                        pan1.Visible = true;
                    }
                    else
                    {
                        pan1.Visible = false;
                    }
                                       //datatbind(wtID4);
                }
           
}