recurse functions

I'm writing a little tool for walking the Windows registry tree, and my question is: can I use function recursion?
And, if yes, maybe someone could explain me more exactly the meaning of a "local value" ($R1-$R9)?
Could I use these variables and forget to push/pop them?

thanks in advance...

There is no difference between $0-$9 and $R0-R9. You only have to push/pop 'em if you want to get the original value back when your function is ready.

To use recursion you have to push them. They were named local so people will use them in local functions and then forget about Push/Pop, but that didn't work so they are just used everywhere. BTW, there is a recursion example in Examples\rtest.nsi.