Describable regularity of the universe. Higher-level phenomena strictly obey lower-level laws, **but instantiate additional lawful regularities that are not derivable in any tractable or explanatory way from the lower level alone**. A rule (a law of nature) is a conceptualized, articulated, grammaticalized pattern.
enables the representation of associative (non-hierarchical) links, which can also be used to represent part-whole links that are not meant as hierarchical relationships.