vtlib uses third party libraries to enable certain functionality.

1. For creating and unpacking zip files
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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.
