The USVN project supports GoPHP5 initiative to help transition to PHP 5.2.
Starting now we will accept PHP 5.2.X features into our codebase and our new feature releases will no longer provide support for older PHP versions.
USVN is already fully compatible with all the PHP 5.X versions and doesn't support PHP 4 but next versions will require PHP 5.2.X because we use some functions of this version related to dates.
For more information please read: