Drupal: what's the Drupal id for the "Save Button"?

what's the hook for the Save Button in Drupal ?

I've tried

  $form['submit']['#weight']  = -50;

But it doesn't work. I'm sure the template.php file works because for example:

  $for开发者_高级运维m['author']['#weight']  = -50;

works.

Thanks

---

The node form is built by node_form().
All of the buttons at the bottom of the form are contained in $form['buttons'], so the information for the submit button is $form['buttons']['submit']