A common use case for rule technologies is that an user organisation needs to switch rules from one rule product to another, and does not want to re-develop their rules. This requires rule interchange in a common format.
Another common use case is when two or more users/organisations need to interchange rules, for execution or further development, while remaining independent in the choice of the rule platform. A typical illustration of that use case is policy or regulatory compliance, where rules representing policies or regulations are developed or imposed by one user/organisation and applied by other ones, and the organisation owning the rules or requiring their application does not or cannot impose a (vendor) specific execution platform. A particular case is the rule-based implementation of a contract (where the rules are owned not by one but by all the parties, and are applied by all as well).
As far as rule interchange is concerned, these use cases have the common characteristic that the form of the rules and how they are used are known to all the parties in the interchange and common to all the rule systems involved. That is, all the rule systems involved share a common meta-model of the rules, and all their implementation-specific rule languages share a common abstract syntax.