Bind variable - missing/00 legth value

During a tuning session I've noticed that the bind variable value was missing in the trace file (10046, level 12) and the avl(Actual value length (array length too)) is 00. Does anybody know what this means?

PARSING IN CURSOR #23 len=339 dep=1 uid=83 oct=3 lid=83 tim=813439884 hv=2248875615 ad='95d38d6c' SELECT IDPHOTO,NICKNAME,TO_CHAR(UPD_TIME,'DD-MON-YY HH24:MI:SS'),URLMYBOX FROM FV_DETAILS WHERE IDPHOTO = (SELECT IDPHOTO FROM  (SELECT IDPHOTO FROM (SELECT IDPHOTO FROM FV_DETAILS_DAY WHERE IDCAT = :b1 AND IDDAY = (SELECT MAX(IDDAY) FROM FV_DETAILS_ DAY ) ) ORDER BY DBMS_RANDOM.VALUE ) WHERE ROWNUM = 1 ) AND IDSTATUS = 20 END OF STMT
EXEC #23:c=0,e=7,p=0,cr=2,cu=0,mis=0,r=0,dep=1,og=4,tim=813439884 FETCH #23:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,tim=813439885 BINDS #23:
 bind 0: dty=2 mxl=22(21) mal=00 scl=00 pre=00 oacflg=03 oacfl2=1 size=24 offset=0    bfp=01a51c28 bln=22 avl=00 flg=05
EXEC #23:c=0,e=0,p=0,cr=2,cu=0,mis=0,r=0,dep=1,og=4,tim=813439885 FETCH #23:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,tim=813439885 BINDS #23:
 bind 0: dty=2 mxl=22(21) mal=00 scl=00 pre=00 oacflg=03 oacfl2=1 size=24 offset=0    bfp=01a51c28 bln=22 avl=00 flg=05
EXEC #23:c=0,e=0,p=0,cr=2,cu=0,mis=0,r=0,dep=1,og=4,tim=813439885 FETCH #23:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=4,tim=813439885

Regards
Dimitre Radoulov

--
http://www.freelists.org/webpage/oracle-l