content categories and keyword linking - what's the relation to the PDG?

Suppose an article on ArXiv had full markup with PhysML and ScienceWise. While useful in aggregate for search, it's not clear how those would relate to the Physics Derivation Graph.

The ScienceWise concept of linking keywords to a database would need to be expanded to linking variables to a database. Then one paper using "x" for position and another paper using "d" for position could link to the same variable definition (independent of symbol used).