question for Commerce owners re: invoices

[LiquidFractal]

I asked this question a couple of months ago in Pre-Sales Questions but it fell into oblivion without a response. 

Anyway - I remember setting up a demo account just to get my hands on Commerce to see how it operates in the suite.  Somebody please correct me if I'm wrong, but I was a bit frustrated working with invoicing and it didn't seem to me as if one could manage invoices by giving them one's own invoice number.

If I remember correctly, when you generate an invoice for a purchased service there is a number which the customer can see, and which can be edited, but I seem to remember that this was pretty useless if I, as site owner/admin, wanted to apply to this invoice my own private internal invoice number for my own records, to manage invoices for tax purposes, etc.  I remember being unable to find a way to add this private invoice code - there's only one code whichis shared with (and editable by) the customer.

Again, if I'm misremembering someone please tell me - I just don't have the time right now to request another demo with Commerce and tinker with it.

[opentype]

There is a purchase order number field, which could be used for that. It’s easy to edit in the ACP and appears on the invoice as well when your print it. I am not aware of any “private fields” which are specifically made for the use you describe.