Trust in a transaction. In another one of my favorite books  (Design Rules: modularity) there exists the concept of trust between physical components of an integrated system. This book stands in contrast to Nobel Economists’ work in defining the “Firm” and organizational boundaries in Transaction Cost Economics (TCE). But the technical theory of modularity is amazingly consistent with the concepts of “boundaries” in TCE. In modularity, there are 4 core rules for separating technical components: