Computer invoicing: XML Extensible Mark-up Language
XML is the Extensible Mark-up Language. It was designed to improve the functionality of the Web by providing more flexible and adaptable information identification. This makes it an ideal tool for data transmission. It is relatively cheap and easy to use. It also allows the use of intermediaries and this makes it preferable to VANS - see VATREC7080.
XSL (Extensible Style Sheet Language) is a variation of XML and works in much the same way. Both XML and XSL are relatively cheap to use and allow small businesses the option to use internet-based commerce for low volume transactions. It is important to note that this is likely to include the transmission and receipt of invoices.