Before revision: We formalize a cumulative interest compliant conservation requirement for pure financial products proposed by Wesseling and van den Bergh to make financial issues relating to these products amenable to mathematical analysis. The formalization is given in a timed extension of tuplix calculus and abstracts from the idiosyncrasies of time measurement .
After revision: We formalize a cumulative interest compliant conservation requirement for pure financial products proposed by Wesseling and van den Bergh by an equation in the framework developed and define a notion of financial product behaviour using this formalization .