A simple UPDATE statement without temporal qualification operates just as an UPDATE on a nontemporal table, completely UPDATING rows that qualify for deletion:
UPDATE employee_vt SET terms='TA07' WHERE ename='Ash';
SELECT * FROM employee_vt;
eid ename terms job_start job_end
---- ----- ----- ----------- -----------
1002 Ash TA07 2003/01/01 2003/12/31
1005 Alice TW10 2004/12/01 9999/12/31
1010 Mike TW07 2015/01/01 2016/12/31
1001 Sania TW08 2002/01/01 2006/12/31
1004 Fred PW12 2001/05/01 9999/12/31
1003 SRK TM02 2004/02/10 2005/02/09