Hi Elliot, I have the answer:
function my_function( $value ) {
if ( empty( $value ) ) :
$value = $_POST['fields']['field_5252ea93ea1f6'] . $_POST['fields']['field_5252aeaf0a86b'];
return $value;
endif;
return $value;
}
add_filter('title_save_pre', 'my_function');
Sorry for the Newbie questions and thanks for your help.
Regards, Ian.