-All the callbacks are expected to return an integer, which is passed straight to the perl magic API.
-However, only the return value of the C<len> callback currently holds a meaning.
+Finally, if C<< op_info => $num >> is also passed to C<wizard>, then one extra element is appended to C<@_>.
+Its nature depends on the value of C<$num> :
+
+=over 8
+
+=item *
+
+C<VMG_OP_INFO_NAME>
+
+C<$_[-1]> is the current op name.
+
+=item *
+
+C<VMG_OP_INFO_OBJECT>
+
+C<$_[-1]> is the C<B::OP> object for the current op.
+
+=back
+
+Both result in a small performance hit, but just getting the name is lighter than getting the op object.
+
+These callbacks are executed in scalar context and are expected to return an integer, which is then passed straight to the perl magic API.
+However, only the return value of the I<len> magic callback currently holds a meaning.