1. A transaction system to audit transaction data for a multitude of different transaction parties as a function of predefined contract terms data defined for a buyer of merchant offerings and a seller of the merchant offerings for each transaction, the system comprising: a data-storing memory circuit that stores the contract terms data and data element specific classification rules, a software-programmed circuit configured, for each of a multitude of sets of transaction data, to respond to activity involving a transaction for at least two of the parties, by accessing the memory circuit and retrieving stored transaction data therein for the transaction; execute an identification algorithm, using the retrieved transaction data, to identify selected ones of the data element-specific classification rules pertaining to the transaction parties; select one of a plurality of data-auditing algorithms respectively programmed on behalf of disparate entities; and execute the selected data-auditing algorithm to audit individual data elements within the transaction data set using the retrieved transaction data, the contract terms and the identified data element-specific classification rules as inputs to the algorithm to generate an output indicating a validation condition for each data element.