adding a Reference Number / PO Number

null@example.com (netracer) — Thu, 13 Nov 2014 09:53:59 +0000

I have invoices to create that require inclusion of reference number / purchase orders number.
Noticed that under credit invoices, the Customer Reference 'can be used' to accommodate it.

However, for Cash Sales ( where customers paid up before shipping ), there is no Customer Reference textbox.

Please advise the alternatives / possibilities available.

FrontAccounting forum — adding a Reference Number / PO Number

adding a Reference Number / PO Number