in new_form_instan ce on form level
Code:
DECLARE 
CurrTime TIMER; 
OneSec CONSTANT NUMBER := 1000; 
BEGIN 
CurrTime := CREATE_TIMER('CURRTIME',OneSec,REPEAT); 
END; 


in when_timer_expired  on form level

DECLARE 
ExpTimer VARCHAR2(40) := Get_Application_Property(TIMER_NAME); 
vTime Varchar2(30) := :SYSTEM.CURRENT_DATETIME; 
BEGIN
...