Electronic invoicing has changed the manner in which invoices and other transaction documents are issued and circulated in commercial transactions and transactions involving self-employed professionals. It has not, however, altered the fundamental procedural requirement that a claim be evidenced in writing in order for an enforceable payment order to be issued. Accordingly, the legal basis giving rise to the claim, the amount of the claim and its acceptance by the debtor must be established by documentary evidence. The critical issue, therefore, is not merely whether there exists a valid electronic invoice bearing a Unique Registration Number (MARK) in myDATA, or whether the invoice has been transmitted to the Independent Authority for Public Revenue (AADE) through a private electronic invoicing service provider. Rather, the documents submitted in support of the application, taken as a whole, must establish that the debtor is bound by the underlying transaction — whether a sale, a