The registering of CallableStatement out (out, inout, return) parameters should be used to
1. help resolve the procedure - if there is a type mismatch or a parameter requested that doesn't exist an exception should be thrown.
2. determine what out parameters the driver should know about. currently the driver is supplied with all out values regardless of how many are registered. this means that the user may not get the right value if the statement does not fully specifier all out parameters.