Quick question about closing PHP tags

There's some discussion going on -discuss about whether or not to close PHP tags. The Zend Framework says to not use them... http://framework.zend.com/manual/en/coding-standard.php-file-formatting.html#coding-standard.php-file-formatting.general Is there any opinion from the internals/PHP experts on this? Is there any technical or performance reason to include them or go without them? Obviously the bonus is no stupid human error/whitespace type issues with output buffering and such. But I wanted to know if there's any opinion either way for any other reasons? Thanks.