1. A method of managing purchasing contracts between supplier entities and customer entities for the purchase of products, said method comprising the steps of: generating at least one purchasing contract between at least one supplier entity and at least one customer entity, the purchasing contract being applicable to one or more contracted purchasing transactions effected, at least partially, through a computerized system, said generating step including defining one or more contract terms, each contract term having one or more term attributes, and storing a term data set of the term attributes associated with each contract term in one or more computer databases; collecting sets of transaction data relating to one or more purchasing transactions; storing the transaction data sets in one or more computer databases; identifying one or more sets of transaction data as a contract transaction data set for a contract transaction identifiable with a contract term; and generating a collection of contract transaction data sets by associating the transaction data set of each identified contract transaction with each term data set of a contract term with which the transaction is identified.