Invalid rowid format in dedlock's trace file

The Oracle version is 9i rel 2
The O/S version is Solaris 9

From the foolwing trace file of a dealock, I want to know why the rowid contains "/" ? There is a rowid "AAAIH/AArAAAj61AAU".

Secondly this deadlock is due to row locking or transaction layer locking ?

Oracle process number: 62
Unix process pid: 26761, image: oracle@piranha (TNS V1-V3)

*** 2003-08-21 11:23:07.934
*** SESSION ID:(63.37) 2003-08-21 11:23:07.906
DEADLOCK DETECTED
Current SQL statement for this session:
UPDATE das_SPOT
SET das_assigned_flg = 'N',
das_assigned_flg = 'N'
WHERE das_key = :b1
----- PL/SQL Call Stack -----
object line object
handle number name
924e70ec 198 package body abc.das_DEASSIGN_PKG
97763e3c 1 anonymous block
The following deadlock is not an ORACLE error. It is a
deadlock due to user error in the design of an application
or from issuing incorrect ad-hoc SQL. The following
information may aid in determining the deadlock:
Deadlock graph:
---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name process session holds waits process session holds waits
TX-00020021-0002d6e6 62 63 X 64 61 X
TX-000d0004-0000069f 64 61 X 62 63 X
session 63: DID 0001-003E-000087CE session 61: DID 0001-0040-0000BCBC
session 61: DID 0001-0040-0000BCBC session 63: DID 0001-003E-000087CE
Rows waited on:
Session 61: obj - rowid = 00008201 - AAAIIBAApAAAnx3AAA
(dictionary objn - 33281, file - 41, block - 162935, slot - 0)
Session 63: obj - rowid = 000081FF - AAAIH/AArAAAj61AAU
(dictionary objn - 33279, file - 43, block - 147125, slot - 20)
Information on the OTHER waiting sessions:
Session 61:
pid=64 serial=101 audsid=153560 user: 44/
O/S info: user: wsadmin, term: pts/3, ospid: 26555, machine: popup
program: java@popup (TNS V1-V3)
application name: java@popup (TNS V1-V3), hash value=0
Current SQL Statement:

SELECT astad.txm_lvl_key,
astad.copy_key,
astad.copy_ref_no,
astad.rotn_no,
astad.sub_rotn_no,
astad.rotn_pat_no,
astad.prod_occr_no,
astad.overlay_key,
astad.icopy_ref_no,
astad.irotn_no,
astad.isub_rotn_no,
astad.irotn_pat_no,
astad.iprod_occr_no ,
DECODE(astad.irotn_no,NULL,DECODE(astad.overlay_key,NULL,'N',DECODE(das1.icopy_assigned_flg,'M','N', 'Y')),'N') glued_icopy_flg,
DECODE(astad.overlay_key,NULL,'N','Y') icopy_assign_flag,
DECODE(astad.copy_key,NULL,'N','Y') avcopy_assign_flag
FROM das_TXM_AREA_DTL astad,
das_SPOT das1
WHERE das1.spot_key = :b1
AND astad.spot_key = das1.spot_key
FOR UPDATE
End of information on OTHER waiting sessions.

Deba