Lock types

SELECT sn.username, m.sid, m.type,
        DECODE(m.lmode, 0, 'None',
                        1, 'Null',
                        2, 'Row Share',
                        3, 'Row Exclusive',
                        4, 'Share',
                        5, 'S/Row Exclusive',
                        6, 'Exclusive',
                lmode, ltrim(to_char(lmode,'990'))) lmode,
        DECODE(m.request,0, 'None',
                         1, 'Null',
                         2, 'Row Share',
                         3, 'Row Exclusive',
                         4, 'Share',
                         5, 'S/Row Exclusive',
                         6, 'Exclusive',
                         request, ltrim(to_char(m.request,
                '990'))) request, m.id1, m.id2
FROM v$session sn, v$lock m
WHERE (sn.sid = m.sid AND m.request != 0)
        OR (sn.sid = m.sid
                AND m.request = 0 AND lmode != 4
                AND (id1, id2) IN (SELECT s.id1, s.id2
     FROM v$lock s
                        WHERE request != 0
              AND s.id1 = m.id1
                                AND s.id2 = m.id2)
                )
ORDER BY id1, id2, m.request;
/

From a thread at sql.ru.