I learned about the three-way match way before I ever heard about EDI. It was done in a large office that had many, many clerks with big stacks of paper all over their desks. I first heard of EDI when I was in Finance and got put on a team to study what we could do with EDI. You guessed right if you said our first and most important project should be the three-way match.
What is the three-way match (sometimes called three-way correlation)? For an expert accounting definition, I turned to the Accounting Coach for an explanation:
In accounting, the three-way match refers to a procedure used when processing an invoice received from a vendor or supplier. The purpose of the three-way match is to avoid paying incorrect and perhaps fraudulent invoices.