Adding Fax Number Field to Packing/Invoice

[mnemos]

Sorry for being a moron, I've entered this code in invoice.php, how do I display it on the invoice?

[Ajeh]

depending on where you want it, you can use:
echo 'The Fax Number is: ' . $customers_fax;

Or, add it to something that already exists on the display ... the variable itself is the:
$customers_fax