I am upgrading imanager version 3.01 to 3.5.

After reading the migration document, I have a doubt on driver upgrade

In the chapter 2.3 "Upgrading Drivers to the New Architecture" is written
... For the new architecture to work properly, all of the drivers in a
driver set must use the new architecture.
You use Designer or iManager to upgrade drivers, after Designer 2.0 and
Identity Manager 3.5 plugins for iManager are installed. These procedures
upgrade the driver to use the new architecture, but it does not upgrade
the driver configuration file.....

What's it means upgrade the driver without upgrade driver configuration

Can I upgrade the drivers without upgrade the driver configuration file or
this operation is mandatory?

Best Regards
Gaetano Nisi