o have an id form a value/option
pair which is not exactly the same as the value. This is used in json requests
for example for selectdyn control.
=head3 get_datasource_controls
returns additional req->Escape ($req -> {json} -> encode($addtop), 6) ;
}
if ($addbottom)
{
$append .= '&' if ($append) ;
$append .= '&addbottom=' . $epreq->Escape ($req -> {json} -> encode($addbotto