Zend_Version provides a class constant Zend_Version::VERSION that contains a string identifying the version number of your Zend Framework installation. Zend_Version::VERSION might contain "1.7.4", for example. The static method Zend_Version::compareVersion($version) is based on the PHP function version_compare(). This method returns -1 if the specified version is older than the installed Zend Framework version, 0 if they are the same and +1 if the specified version is newer than the version of the Zend Framework installation.