Does each field have only A-Z0-9 characters?

If so,
$_ =~ /((\w{12})\n)/;
$1 = the 12 digit field plus the newline, while $2 = the 12 digit field without.

If you need other characters, you could use
$_ =~ /(([A-Za-z0-9\.\+\-]{12})\n)/;
To get alphanumerics and '.', '+', and '-'.

John J Reiser
newrisedesigns.com