To aid in upgrading with minimal change, the Author did not change the names of the units for Addict 4 - so many of them still have ad3 prefixes...
In hindsight, we admit that we shouldn't have named the Addict 3 units this way - but when Addict 3 came out 8 or so years ago, we wanted to have Addict 3 and Addict 2 co-existing since the "approach" changed quite significantly - whereas with Addict 4 we wanted most of our customers to only need to do minimal (if any) change to get their current Apps working with Addict 4, and then update components and/or use new features as they wished.
Some further info in the FAQ - see in particular:
http://www.addictive-software.com/phpBB ... p?f=3&t=12