whats in the $string:
0a0a0a0a0b0b0a0a0c0c0c0c0c0c0c0c
1f1f2b2b2b2b3e3e7b7b7b7b7b7b7b7b
8f8f8f8f8f8f8f8f6c6c4b4b4b4b3f3f
9d9d0f0f0f0f0f0f0f0f3a3a2e2e2e2e

##</code><code>##

$string =~/\d{2,4,8}/\/[0-9a-fA-F]/;
or
$string =~/\w{2,4,8]/\/[0-9a-fA-F]/;