Next version of QuickForm should be?..

Hi, There is a good chance that work on a new major version of HTML_QuickForm package will start soon, this would be a PHP5-only package with a quite different API. Now, as QuickForm existed long before current guidelines for package versioning were established, its current version is 3.2.5 but the package name has no number appended. Therefore, a question. Should a new version be HTML_QuickForm2 or HTML_QuickForm4? HTML_QuickForm2 with versions starting from 4.0.0 looks a bit stupid, but HTML_QuickForm4 looks a bit stupid, too, since there were never HTML_QuickForm2 and HTML_QuickForm3. I don't see any specific guidelines for this case, but maybe I'm missing something? Suggestions are welcome, also.