TPA in trading networks


I have gone through trading networks document but I do not understand how TPA works? and what is it exactly used for? what is TPA data

In the guide it is quoted that “Trading Networks does not use TPAs for its own processing; rather, the data you
specify in the TPA are available for your own use.” What do we use TPA exactly for?

And what are initialization, validation and export services are used for?

Please help

You could consider TPA as customized configuration file between two partners for specified transaction. You could define some agreements(for example special discount) in TPA. In runtime, you could use build-in service to retrieve TPA data, and use these configured agreements in your process.