If I have the bellow html form...

<form name="form_test" method="post" action="PHP_TEST.php">
<input type="submit" value="Save" name="send_post_save"></input>
<input type="submit" value="Delete" name="send_post_delete"></input>

...how can I set up my PHP_TEST.php page to differentiate if the sender was my 'Save' button or my 'Delete' button.

Thanks