 According to Hughes’ Denotation, Demonstration, and Interpretation (DDI) account of scientific representation (1997, 2010: ch. 5), models denote their targets; are such that model users can perform demonstrations on them; and interpret the results of such demonstrations in terms of the target. The last step is necessary because demonstrations establish results about the model itself, and in interpreting these results the model user draws inferences about the target from the model (1997: 333). Unfortunately Hughes has little to say about what it means to interpret a result of a demonstration on a model in terms of its target system, and so one has to retreat to an intuitive (and unanalysed) notion of drawing inferences about the target based on the  model.[10]