How to use v$session_longops to check long running processes

I am setting NLS_DATE_FORMAT so that the START_TIME and LAST_UPDATE_TIME will be more accurate.

SET TERMOUT OFF
ALTER SESSION SET NLS_DATE_FORMAT='DD.MM.YYYY HH24:MI:SS';
SET TERMOUT ON
SET LINES 300
COL "CURRENTLY EXECUTING" FORMAT A35
COL OSUSER FORMAT A10
COL MACHINE FORMAT A20
COL USERNAME FORMAT A20
COL PROGRAM FORMAT A40
COL UNITS FORMAT A20
COL OPNAME FORMAT A10
COL START_TIME FORMAT A20
COL LAST_UPDATE_TIME FORMAT A20
COL SQL_ID FORMAT A15
SET VERIFY OFF
SET FEEDBACK OFF

SELECT
    S.SID,
    S.SERIAL#,
    S.OSUSER,
    S.MACHINE,
    S.USERNAME,
    S.PROGRAM,
    S.SQL_ID,
    SUBSTR(Q.SQL_TEXT,1,30) || '...' "CURRENTLY EXECUTING",
    L.OPNAME,
    L.SOFAR,
    L.TOTALWORK,
    L.UNITS,
    L.START_TIME,
    L.LAST_UPDATE_TIME,
    L.TIME_REMAINING "SECONDS LEFT",
    TO_TIMESTAMP(L.LAST_UPDATE_TIME,'DD.MM.YYYY HH24:MI:SS')-TO_TIMESTAMP(L.START_TIME,'DD.MM.YYYY HH24:MI:SS') "RUNNING FOR"
FROM V$SESSION_LONGOPS L JOIN V$SESSION S ON L.SID = S.SID
                         JOIN V$SQL Q ON S.SQL_ID = Q.SQL_ID
AND   S.SID = &SID
AND   S.SERIAL#  = L.SERIAL#
ORDER BY L.LAST_UPDATE_TIME DESC;

EXIT

Result:

SID	SERIAL#	OSUSER	MACHINE	USERNAME	PROGRAM	SQL_ID	CURRENTLY EXECUTING	OPNAME	SOFAR	TOTALWORK	UNITS	START_TIME	LAST_UPDATE_TIME	SECONDS LEFT	RUNNING FOR
408	2624	oracle	testserver1	SH	sqlplus@testserver1 (TNS V1-V3)	3w11rcbvd5a32	UPDATE SALES_Q1_DI_MASTERS SET ...	Table Scan	82432	82636	Blocks	06.03.2014 07:35:26	06.03.2014 09:44:22	19	+00 02:08:56.000000