PHP Code Tags

What about <?= ?> and <?php= ?> ?

It's applicable in any script which ends with PHP code, e.g.

<?php
// Something here
?>
<div>Some HTML here</div>
<?php
// Some other code here?>

Not including the closing ?> is only applicable when the file only contains PHP code.

Drupal code styles suggest avoiding the final closing ?>.

They do so as to minimize the chance of content being sent by whitespace (sometimes inserted by FTP clients) after the closing town, which may prevent proper sending of headers.

Does PEAR care either way? Is it OK to avoid the final closing PHP tag?