Meaning directs our attention to things – in Part 1, we called this “reference.” Meaning tracks our activity as sensuous creatures – in Part 2, we called this “agency.” Meanings also hang together, with networks of interlinkage that create coherence, where every meaning is greater than the sum of its parts. In this part, we are going to name this coherence, “structure.” Analysis of the holding together in structures, we call “ontology,” or the philosophy of what things are, their being. We identifying two kinds of binding, two kins of ways in which things hold together in the work: in material structures (the meanings-in things themselves), and ideal structures (the meanings-for those things, the meanings we attribute to them). The process of interconnecting the material and the ideal, we call design. In forensics that analyze ontologies and their designs, we look for specific relations. This is to make our analysis more granular. However, heading the other way, towards ontologies with higher levels of generality, we find ontologies encompassed by more general ontologies, or metaontologies. Structures can nest with in structures.