I have a small amount of basic & C++ experience - but years ago....& a lot has changed!
So I have to learn/recall again.  
What had thrown me was the fact some vars were defined with 
= function & some not
eg
@var $arr = GetSourceSelectedPaths();or
@var $ext;Until you put the 
$ext in the loop, it obviously returned a single extension value for multiple different file types.
I since realized that assigning values to vars is conditional on the context.  [Cannot say why I forgot that!! 

]
Returning multiple ext values was dependent on the loop cycling.  
But I can see where both options could be used
- make all exts the same
- keep all exts as is.
I started thinking about the names being the same on multiple files with the same .ext.  Obviously this is made irrelevant by the use of Multi-rename, but I started to think about how to add that to the script as an experiment.  
I started with the idea to only name 1 file & now there is a holocaust of bad code imminent!!  

There are quite a lot of interesting possibilities in MC Script & I enjoy playing around with it.  Sorry for the torture it creates.  

I will have to look at some programming tutorials, to reduce the time I spend creating comedy scripts for you. 
