PLAN TABLE

Query:

SELECT, COUNT (DISTINCT T.DTC_CTRL_NO)
FROM DEVLBGTM.A_GTM_TCNF T
,DEVLBGTM.A_GTM_UGRP_ACS U
,DEVLBGTM.A_GTM_SMAC_AC_DTMN S
,DEVLBGTM.A_GTM_TCNF_PRTY P
WHERE U.USR_GRP_ID = 'GRP028300'
AND P.PRTY_ID = '00080901'
AND P.PRTY_ROLE_CD = '01'
AND P.DTC_CTRL_NO = T.DTC_CTRL_NO
AND T.DTC_CTRL_NO = S.DTC_CTRL_NO
AND U.SMAC_SYS_CD = S.SMAC_SYS_CD
AND U.SMAC_ACCT_NO = S.SMAC_ACCT_NO
AND T.CNFRM_STAT_CD <> 'CNCL'
;
I have following explain plan output:

PLANNO, METHOD, TNAME, ACCESSTYPE
----+---------+---------------------------------
1 0 T_GTM_TCNF_PRTY I
2 1 T_GTM_UGRP_ACS I
3 1 T_GTM_SMAC_AC_DTMN I
4 2 T_GTM_TCNF R

Can you please explain the sequence of operations here?