vtlib is a library to ease new module development for vtiger CRM. vtlib includes APIs to create or modify the backend elements for a module. These APIs help make the necessary changes to the database.
vtlib includes Module Manager which allows new modules to be packaged into zip files that other vtiger CRM installations can easily install and use.
For vtiger 5.0.4, vtlib is available as a download. This package needs to be installed by developers as well as users who intend to install modules developed using vtlib.
vtlib will be integrated in vtiger CRM version 5.1 download.
http://forge.vtiger.com/projects/vtlib