PQresultStatus for a transaction

in my c code I have a call like the following:

rs = PQexec(conn, "BEGIN; UPDATE userinfo set batchno=0; UPDATE
adschedule_items set batchno=0;COMMIT;");

the question is this: when checking for failure of the above transaction, how
do I check if the above transaction failed? do i use PGRES_COMMAND_OK?

- Martin -