Thanks Mathias.
I got confused with 
$arr - when it was present the script completed one pass, but not the rest of the selection.  (As you must realize).
So I left 
$arr in order to get the operation to complete & thus find out which part of the regex 
would work.  
I started using perl type commands but as you say the 
StrRegExpReplace function won't allow me to do a 'batch' of separate ops.
Took me a while to see which string was the right one with which to replace $arr.  But I now have a better array usage! 
This will make changes to multiple selections now (not what I want of course but better from a script point of view.) -
@var $arr = GetSourceSelectedPaths(); 
@var $items = arrayCount($arr);
@var $CurrentNameFullPath;
@var $OrgName;
@var $re = "\w.";
@var $result;
@var $n = 0;
for( $n = 0; $n < $items; $n++ )
{
  $CurrentNameFullPath = $arr[ $n ];
  $OrgName = PathGetNamePart( $CurrentNameFullPath );
  $result = StrRegExpReplace($OrgName, $re, " ");
  
  RenameFile( $CurrentNameFullPath, $result, "SILENT" );
  
  }I cannot use ( ) within the 
$re define multiple segments, soI think I would have to do a loop of repeat operations to change each element individually.  Quite frustrating when I can run the regex's I posted in a text editor on text & get the right result.   
Regular Expression Editor (RegExpEditor), amongst others, on sourceforge could be useful for regex types.
Well I guess that is enough headache for one day.   

+++
UpdateThought I'd add the regex I was using to change the date field I mentioned above for clarity.  (I was showing the whole string as regex transpositions instead of in -> out)
10_May_1989 -> 10 May 1989
find - 
((?:[0-9]+)+)_((?:[a-zA-Z]+)+)_((?:[0-9]+)+)replace - 
\1 \2-\3I think I can see a way for each \#<match> for be given its' own instruction.  More headaches req'd.
The main advance for me here is the visualization of matrices in your script.  I was thinking more DOS Basic & linear commands.  Matrix application is more dynamic of course.  So thanks for forcing me down that road.   
