Interlibr federates repositories of rules providing the facility for rule-takers to match rules that are applicable to their data and to apply those rules over their data. An index of rules is maintained by Interlibr and provided to rule-takers. This index enables a basic matching algorithm to be run by the rule-taker:
A rule is effective if it matches the jurisdiction (country and region) specified in a transaction. If effective dates and times are specified in the expression of the rule, then the date and time in the transaction must fall within this effective period.
A rule is applicable if applying the rule would recommend changes to the information offered in the transaction. When writing the rule, the rule-maker supplies a set of conditions on the transaction data that would indicate whether their rule would recommend changes when those conditions are met. For example, a rule that calculates a conditional value-added tax might require that the transaction data include fields that specific price and product classification.
On first glance, it seems as if effective and applicable are very similar and could possibly be expressed in a single manner. Therefore, we should consider why the two different ideas exist.
The rules that are indexed by Interlibr are each entries in a large ontology classified according to industry, jurisdication, time, etc. The effectiveness of a rule is a form of meta-organization within this ontology. Rule-makers are able to use this classification to broadly partition documents that will be processed. Therefore, in-effect is the classification of a rule.
Each individual rule represents a very small program or computation. As part of the expression of this computation, we can indicate what types of data a rule will affect. Knowing whether a rule will result in anything allows us to eliminate rules that do nothing, saving computation time. To do this pruning, specific information about the rule and specific introspection of the transaction data is required. Therefore, we intentionally perform this second partition as a distinct phase.