We describe a classification of 4d N=2 superconformal theories
obtained from the compactification of 6d N=(2,0) A_N theories on
punctured Riemann surfaces. We show the basic building blocks to
construct any such theory and its various S-dual frames. A host of new
S-dualities and interacting (non-Lagrangian) superconformal theories are
unconvered. We also compute various properties of these interacting
superconformal theories.