Two, Three, Four and Five Corner Models

There are four different models of e-document transfer used today.

The different models for e-invoicing and e-trading have evolved over time.  At the inception of electronic trading, organisations would initiate a direct connection (2 corner) to exchange electronic business documents - such as invoices and orders - between themselves.  Over time service providers entered the market in order to manage the complexities inherent when organisation adopt different file structures and communication protocols (3-corner).  They were also driven by a strategy to connect organisations to their own private network and create value added communities for their clients.

Today as we see the concept and development of Pan-European and Global networks the 4-corner and even the 5-corner model has arrived.

The 2-corner model

The 2-corner model is a P2P (peer to peer) process where the supplier and buyer directly share e-documents with each other’s systems, typically sending/receiving EDI or XML file structures.

2 corner model

The 3-corner model

The 3-corner model is where the supplier/buyer use the same third-party service provider to exchange e-documents between them. The third-party service provider would typically offer services such data translation, mapping and validation services before generating an EDI or XML file structures that are delivered to the receiver.

3 corner model

The 4 -corner model

The 4-corner model is where the supplier/buyer use different service providers (also known as Access Points) to exchange electronic (e.g. invoices, orders, order acknowledgements, etc). In the 4-corner model the service provider adhere to an interrogability protocol, such as PEPPOL, in order to exchange documents with other service providers (aka Access Points).

This can be likened to the model used mobile telephone operators where each mobile phone is assigned to a network supplier and they must work together to connect their client.  The service providers have agreed to be interoperable, so that once a supplier is connected to a network, they become part of the wider network and can exchange documentation with any buyer on the network.

4 corner model

The 5 -corner model

The 5-corner model is where central entity (often a government agency) acts as the hub by which all transactions flow between Access Points.  This model is often used in government sponsored initiatives (e.g. Italy), where central government want to track tax commitments.  

PEPPOL (Pan European Public Procurement Online)

PEPPOL is a European initiative based on the 4-corner model that enables companies and government organisations (such as the NHS) to exchange e-documents over an interoperable, European-wide network. Simply put, it offers a standardised network to connect business and organisations for electronic ordering, shipping and invoicing. Users are able to connect to all other users through Certified Access Points. Each user will have their own unique identifier or address, like how phone numbers work.

Find out more about CloudTrade's PEPPOL Certified Access Point services for:  

NHS buyers     NHS Suppliers

Read more about PEPPOL at

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