Four corner type and interoperability crucial achievement elements for automated invoicing.

Electronic invoicing is normally an innovation that enjoys significant positive network effects. The more companies we get into the electronic invoicing network, the more valuable is the technology for the nodes in the network. Just like telephone network, fax network, facebook etc. Metcalfe s law states the value of this kind of network is proportional to the square of the amount of connected users of the system (n2).

http://realtimeeconomy.net/blogs/show/1/3/286/Four-corner_model_and_interoperability_critical_success_factors_for_electronic_invoicing_-_Esko_Penttinen