Although I don't disagree with the overall thrust of your argument, there is a tiny mistake.

However.. if your text chunk is:

$text='ADABCDE6789023424';
$text=~/([A-Z]{2,5}\d{5})/ or die;
print $1; # will print 'DE67890'
[download]

It actually would print ABCDE67890. Remember the {2,5} matches the longest string it can, unless you make it non-greedy.