gzcompress/gzdeflate default compression level?

From: Gerard Samuel (php-general_at_trini0.org)
Date: 10/29/03 

To: php-general@lists.php.net
Date: Wed, 29 Oct 2003 14:29:39 -0500

The docs do not state what the defaults are, and from tests,
it seems the values 4 - 9 return the same output as with no value,
on the string I tested with.
Does anyone know what the default compression levels are?
Thanks