question about AbstractJdbc2Statement

Hi all,
in the org.postgresql.jdbc2.AsbtractJdbc2Statement#executeQuery there's:

if (result.getNext() != null)
throw new PSQLException(GT.tr("Multiple ResultSets were returned
by the query."), PSQLState.TOO_MANY_RESULTS);

It is not clear to me when an executeQuery could have multiple result sets as
result, since the execution of the query thru the queryexecutor seems to me
to exploit the SendOneQuery method. Is this related to the batch processing
or something I'm missing from SQL? Can somebody explain me when multiple
resultset can be returned from a query?

Thanks,
Luca