where i can find all possible parametres?

[mohamed khounti]

hello i'm trying to render tpl file with index() in controller class but with aditional  parametres.
for example  index.php?m=mymodule

to  index.php?m=mymodule&domain_id=5
can't find a way to do it 
i'm using this function to render and pass variables to tpl 

return array(
            'pagetitle' => 'DNS manager',
            'breadcrumb' => array(
                'index.php?m=dns_manager' => 'DNS manager',
            ),
            'templatefile' => 'dns_manager',
            'requirelogin' => true, // Set true to restrict access to authenticated client users
            'vars' => $vars,
        );


how too add parameters to the url