Then the idea of using [INVOICE_ID]as the invoice number doesn´t work either, since it corresponds to baskets and not to really invoices.
On the new release you are preparing, with the option to create sequential numbering for the invoice, will that number apply only and exclusively to real invoices (the ones really paid) or will the system generate a number for a basket (an invoice not really issued an paid) that may be deleted creating number gaps between the real invoices. If this is the case, it is absolutely useless in legal terms.
Please, do have this in consideration, I think it is important to many people.
Than you.