It's dynamic distance modifier. It allows you to express a formula which changes the 'd' polar coordinate depending on a formula. Sort of a more limited version of the dynamic movement, but it works differently.
...is there any kind of demo or tutorial for those two items? I think that if I add those (or one of them) to my presets they may get better...
There's a few. A pretty detalied one went on between nic01 and cmountford. I think its "Sneak peek at AVS pack" in the presets section. Do a search, look at the Unconed's FAQ. You'll find something.
Luusaved, welcome to the forums and thanks for your detailed answers.
Just to make sure you know this, the date above the usernames are the dates when the posts were made. You are replying to questions that were asked 13 years ago.