RIF must define for all RIF elements a default behaviour for compliant applications that do not know how to process it
Full Statement
All RIF(Core, Standard, etc) elements must define a default behaviour for RIF (Core, Standard, etc, resp.) compliant applications that do not know how to process it. That default behaviour must be easy to implement independently of the rule-processing capability of the consumer application (e.g. "IGNORE ELEMENT", "IGNORE RULE", "IGNORE RULESET").
Position in the DC structure
Level: Requirement [PROPOSED]
Dependencies
The following DCs depends on that one:
Compliant applications must handle any valid RIF document in a predictable way
Support for Priorities and Preferences (cf. Courteous Logic) (from :F2F2/RequirementsBrainstorming)
Graceful Degredation (requirement on translator) -- use the core as much as possible? (from :F2F2/RequirementsBrainstorming)
RIF must be extensible (from :F2F2/RequirementsBrainstorming)
Different kinds of rules to be interchanged (from Draft - Requirements on RIF)
Extensibility in the sense that users can add customized functionality (data transformations, access to new data sources). (from Draft - Requirements on RIF)
This DC is (or may be?) an alternative to the following:
Identifying which member of the family of possible dialects is used in this Ruleset (from :F2F2/RequirementsBrainstorming)
Each feature-package labeled about which other feature-packages it is compatible with (or maybe the users/programmers need to know this, not the machines) (from :F2F2/RequirementsBrainstorming)
Format for tagging of various RIF extensions (in a way that rule engines can announce their capabilities in these terms and compatibility between a rule set and a rule engine can easily be determined). (from Draft - Requirements on RIF)
Requires that RIF support the intersection of features found in competing products (from Draft - Requirements on RIF)
Decidability or possibility to automatically restrict to an expressive decidable fragment (from Draft - Requirements on RIF)
Motivation
See Compliant applications must handle any valid RIF document in a predictable way
This DC is equivalent with the following:
Graceful failure -- if RIF->RL1, some feature can't be done correctly, then there should be some proscribed behavior (from :F2F2/RequirementsBrainstorming)
See also a simple proposal how this could work in my answer to Dave Reynolds about decidability.
Urgency
A RIF without that is probably of limited use for most stakeholders