vtlib uses third party libraries to enable certain functionality. 1. For creating and unpacking zip files -- ==================================== vtlib/thirdparty/Dzip.php vtlib/thirdparty/dUnzip2.inc.php DOWNLOAD URL: http://www.phpclasses.org/browse/package/2495/ BSD License: http://www.opensource.org/licenses/bsd-license.html NOTE: Bug Fix was added to function addFile of dZip class.