The scaling of both the L-H threshold and confinement with themass M of hydrogenic isotopes is discussed. The confinement was found to scale differently with M in the core and the edge, and a tworegion model has been developed to represent the physical behaviour ofeach region. Identity pulses with the same profiles of the dimensionlessphysics parameters ρ*, ν* and β were obtained withdifferent isotopes, H and D; this result suggests that there is noexplicit mass dependence of the transport in either the core or the edge region.