Fig. 4. : Flow between states. The flow measures the difference between two continuous assignments A and B by subtracting the vectors (∆AB). The arrows describe the probability flows necessary to turn A into B, i.e. the flows from positive values to negative values in ∆AB. These are treated as probability flows, as illustrated in (b), where the flow from state T (value 9) to state H (value -10) is relatively larger than that from state T to state G (value –4, see eqn. 6 . By analysing the flow between continuous assignments, we can describe the overlap and/or exchange of assignment propensities for individual secondary structure states.