1. A computer program product tangibly embodied in an information carrier for defining a custom computer-executed business process for a particular business enterprise, the computer program product comprising: a generic component that includes generic data attributes and instructions that, when executed, cause generic transaction data to be processed in a manner that is applicable to many different business enterprises; a rule handling component that includes data structures and instructions that, when executed, cause transaction data to be processed in a manner that is applicable to a particular business enterprise; wherein: the data structures comprising: a rule collection data structure to store rule collection data; a rule data structure to store rule data wherein: a rule entry in the rule data structure includes an execution portion that identifies processing of transaction data to be performed when a rule condition associated with the rule entry is met; and at least one entry in the rule data structure relates to at least one entry in the rule collection data structure; and a rule condition data structure to store rule condition data wherein: a rule condition entry in the rule condition data structure includes a condition portion that defines conditions for which the execution portion of a related rule entry is to be executed; and at least one entry in the rule condition data structure relates to at least one entry in the rule data structure; and the instructions that, when executed, cause the rule handling component to perform steps comprising: determining whether a condition portion of a rule condition entry in the rule condition data structure is met, and in response to a determination that the condition portion is met, perform an execution portion of a rule entry in the rule data structure that is related to the rule condition entry.