Exact Multiplets of Spontaneously Broken Discrete Global Symmetries: the Example of $N=2$ Susy QCD

6 pages, uses PHYZZX, to appear in the Proceedings of the Second International Sakharov Conference, Moscow, May 1996, based on a talk given by A.BIn these notes, we emphasize the r\^ole of spontaneous broken global discrete symmetries acting on the moduli space of $N=2$ susy Yang-Mills theories and show how they can be used, together with the BPS condition, as a spectrum generating symmetry. In particular, in the strong-coupling region, all BPS states come in multiplets of this broken symmetry. This played a key r\^ole in the determination of the strong-coupling spectra