How User control can call with out Register in ASPX page

if you add or call user control in web configuration

<configuration>
<system.web>
<pages><control>
<add src="../App_Controls/Admin.ascx" tagname="Header" tagprefix="Osnadmin">
<add src="../App_Controls/AdminLogin.ascx" tagname="LoginHeader" tagprefix="Osnadmin">
<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.UI" tagprefix="asp">
<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.UI.WebControls" tagprefix="asp">


</add></add></add></add></control>
</pages>
</system.web>
</configuration></div>