scn号很大，转换16进制数后超过8位 怎样通过bbed修改？

select to_char(20168425658,'xxxxxxxxxxxxxxxx') from dual;

TO_CHAR(201684256
-----------------
        4b221c0ba

BBED> assign kcvfh.kcvfhckp.kcvcpscn.kscnbas  = 20168425658
BBED-00207: invalid offset specifier (20168425658)