Excellent! Thank you. I've not used "map" before so will have to study that one.

Regarding the use of \b, I'm wondering if my hash name contains a period at the end, what would happen? This seems to work fine but am I causing a potential problem? I guess my question is, since . is also a word boundary, might it leave it in in the substitution?

%subs = ("Xaa1." => "sub1");
foreach $s (keys %subs){
$data =~ s/\b$e\b[.]?/$subs{$s}/g;
}
[download]

Anyway thanks much, this is very helpful.

UPDATE:

Ignore that last question. What I meant was, if $data contains a period after Xaa1, not the name in %subs. Here is my Xaa1. data string.

But I think I'm asking a confusing question.. so please ignore. :-)