[en] The basic phenomenology of discharges with core transport barriers is the same for DIII-D and JET. The limitations on performance in both cases are well described by MHD stability calculations. Since the discharge behavior of the two machines is so similar, it seems reasonable to apply a simple parameterization of fusion performance which describes well the best performance discharges on DIII-D. The highest fusion performance shot on JET has Q_DD = 3.1 10^-3 at 3.2 MA. Scaling from the highest Q_DD DIII-D single-null discharge would predict Q_DD = 4.2 10^-3 for JET. Raising the plasma current to 4.0 MA would increase the projection to 6.6 10^-3. Realization of such performance would require significant effort to develop lower q plasmas with an H-mode edge. Because the performance is so closely tied to the current profile, this class of discharges also shows significant potential for steady state if current profile control can be demonstrated