#!/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";