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; an application execution point data structure to store application execution point data wherein an entry in the application execution point data structure identifies an execution point in a transaction process identified in the generic component; an external execution point data structure to store external execution point data wherein: at least one entry in the external execution point data structure relates to at least one entry in the rule collection data structure, and the at least one entry in the external execution point data structure relates to at least one entry in the application execution point data structure; and the instructions that, when executed, cause the rule handling component to perform steps comprising: when an indication is received that an application execution point is reached in a transaction process identified in the generic component, determine whether an entry in the external execution point data structure relates to the reached application execution point, in response to a determination that an entry in the external execution point data structure relates to the reached application execution point, determine whether an entry in the rule collection data structure is related to the entry in the external execution point data structure, and in response to a determination that an entry in the rule collection data structure is related to the entry in the external execution point data structure, i) identify a rule entry in the rule data structure that is related to the entry in the rule collection data structure, ii) identify a rule condition entry in the rule condition data structure that is related to the rule entry in the rule data structure, iii) determine whether a condition portion of a rule condition entry in the rule condition data structure is met, and iv) 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.