function check_main_node(form, attribute_id, node_id) {

    var elements = form.elements;
    var checkbox_name = 'location_'+attribute_id;
    var checkbox_id = 'node_'+node_id;

    for (var i = 0;i<elements.length ;i++ ) {
        if (elements[i].type == "checkbox" && elements[i].name.match(checkbox_name) ) {
            elements[i].disabled = false;

            if(elements[i].id == checkbox_id) {
                elements[i].disabled = true;
                elements[i].checked = true;
            }
        }
    }
}