In my business, in no way is the printout of the order details an "invoice" (which in my country is a legal document requiring various specific fields), so I have removed all references to it and use "Order" or "Order Details" where appropriate. Otherwise we would get in trouble for using that word on an invalid document.

For us, Zen Cart is a sales channel that collates customer orders. An invoice is generated from our invoicing software with the correct fields.

Just wondering if that is an issue for others / should "invoice" should be changed in the core code?