We present a methodological discussion of how to elaborate different scale epistemological reference models and in particular, present a large-scale model for the domain of arithmetic in Japanese primary school, based on the national program and selected textbooks. Our theoretical base is the Anthropological Theory of Didactic (ATD), specifically the notion of praxeology and the levels of didactic codetermination. We also briefly discuss our motivation for creating such models, namely to analyse how students experience shifts between mathematics in different different school systems.