Berserker, thanks for the code!

There were not many times I struggle with erm syntax, but now it is definitely the moment. It seems like my knowledge is not enough to handle erm 4, lol!
A few questions I'd like to ask:

1. What is (@var)?
2. What's the reason for using y(ptr) here? Is it not true that mixing normal y and (var:y) could result in bad things?
3. What's wrong with my code when I try to execute the function with an array ID? I can't get to define the IF:N dialogue.