If I understand you correctly, the only line you are really interested in is the one with the long string of all_caps letters which you have stored as a scalar element in an array called @se. Instead of one big string, you want that to contain a reference to an array of individual letters?

Have to agree with ptum, but for clarity's sake, the

'unknown' => [];

would get filled with

 'unknown' => {split(//,$_)};

. This could be done with an array of arrays too though... and I would probably go with a hashes of hashes with the last value of each contained hash being the array of letters... But then maybe I am just dazed and confused... :-)