We introduce a definition for a 'hidden measurement system', i.e., a physical entity for which there exist: (i) 'a set of non-contextual states of the entity under study' and (ii) 'a set of states of the measurement context', and which are such that all uncertainties are due to a lack of knowledge on the actual state of the measurement context. First we identify an explicit criterion that enables us to verify whether a given hidden measurement system is a representation of a given couple S, [.

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... onsisting of a set of states E and a set of measurements E measurement system). Then we prove for every measurement system that there exists at least one representation as a hidden measurement system with [0,1] as set of states of the measurement context. Thus, we can apply this definition of a hidden measurement system to impose an axiomatics for context dependence. We show that in this way we always find classical representations hidden measurement representations) for general non-classical entities (e.g. quantum entities). 1 'pure state'. For a well-founded definition of state we refer to [21].