+=item B<-dsaparam>
+
+If this option is used, DSA rather than DH parameters are read or created;
+they are converted to DH format. Otherwise, "strong" primes (such
+that (p-1)/2 is also prime) will be used for DH parameter generation.
+
+DH parameter generation with the B<-dsaparam> option is much faster,
+and the recommended exponent length is shorter, which makes DH key
+exchange more efficient. Beware that with such DSA-style DH
+parameters, a fresh DH key should be created for each use to
+avoid small-subgroup attacks that may be possible otherwise.
+
+=item B<-check>
+
+check if the parameters are valid primes and generator.
+