Well, I'll just address your sorting question/issue--- you can sort on the catalogue number by dividing each one into 3 components: leading non-digits (if any), digits, trailing non-digits (if any) ... and then defining the sort routine to sort on these components. Here's an off the cuff Schwartzian Transform applied to the data:

#!/usr/bin/perl -w
use strict;
my @list = qw/715b E9 715a 614 715 C18 1 4 12a 12/;
my @sorted = map{$_->[0]}
             sort{$a->[1] cmp $b->[1] ||
                  $a->[2] <=> $b->[2] ||
                  $a->[3] cmp $b->[3]}
             map{[$_,/(\D*)(\d+)(\D*)/]} @list;

print join("\n", @sorted),"\n";
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Knowing how to sort on catalogue numbers should relieve you of the need to use a special sort N field in the data. Having said that, you might also want to look into the DB_File dbm system which has a BTREE mode for keeping entries in sorted order (you can provide a comparison routine), and it has facilities for matching partial keys which can be used to code for retrieving ranges.

Hmmm. Ok, I didn't realize that was possible (but I shoulda figured... it's Perl :-) ). Here's a question though: if I don't have DB_File, and I want to display a range of numbers, say 614 - C18, how would I be able to do it without the sort field?

Since you can sort on catalogue number, you can loop over the sorted keys and skip the ones not in the range:

foreach my $key (@sorted) {
    next unless $key eq '614' .. $key eq 'C18';
    print "$key: $db{$key} \n";
}
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Assuming the hash is %db. I suspect you were doing something similar but using the sort N field? The downfall is that you need to get the whole list of keys into memory --- with DB_File that could be avoided.