Higher Order and Frame Based Syntax
Higher-order syntax means that variables can range over function and predicate symbols. In knowledge representation, this is useful, for instance, for exploring the schema of an unknown KB (schema querying).
Frame-based syntax (also known as "slotted" notation) enables object-oriented design and use of knowledge bases with all the ensuing advantages.
Position in the DC structure
Level: [Requirement] [PROPOSED]
RIF without that is of limited use for me / RIF would be better with that