  The results of Romelsberger for a N=1 superconformal index counting protected
operators, satisfying a BPS condition and which cannot be combined to form long
multiplets, are analysed further. The index is expressible in terms of single
particle superconformal characters for N=1 scalar and vector multiplets. For
SQCD, involving SU(N_c) gauge groups and appropriate numbers of flavours N_f,
the formula used to construct the index may be proved to give identical results
for theories linked by Seiberg duality using recently proved theorems for
q-series elliptic hypergeometric integrals. The discussion is also extended to
Kutasov-Schwimmer dual theories in the large N_c, N_f limit and to dual
theories with Sp(N) and SO(N) gauge groups. For the former, a transformation
identity for elliptic hypergeometric integrals directly verifies that the index
is the same for the electric and magnetic theories. For SO(N) theories the
corresponding result may also be obtained from the same basic identity. An
expansion of the index to several orders is also obtained in a form where the
detailed protected operator content may be read off. Relevant mathematical
results are reviewed.
