Hi,
The call of update_course() is made in course/edit.php itself (if you see source code of the edition form, you will see that the action of that form is course/edit.php), passing the data retrieved from the form:
if ($data = $editform->get_data()) {
// Do checks, and then call to update_course($data)
}
I hope this is helpful; otherwise, don't doubt to ask again.Cheers,
Julen