thanks for your reply, about "NO MORE .PRG"

and i have question about variables

FORM_INV is a form for entry the header data of INVOICE NOTE. there have a button (.CLICK) to call up "DO FORM FORM_INV_ITEM LINKED" for input its order itmes.

i create some variables at FORM_INV --> THISFORM.INIT as below:
*****
public TOTAL_AMT, TOTAL_COST, TOTAL_ITEM
TOTAL_AMT = 0
TOTAL_COST = 0
TOTAL_ITEM = 0
*****

but while i go into FORM_INV_ITEM those variables are not valid.
(or at FORM_INV --> THISOFRM.SAVE those variables are not valid too. )
SO i add a INVOICE.PRG file for the master program as below :

INVOICE.PRG program as below :
*****
priv TOTAL_AMT, TOTAL_COST, TOTAL_ITEM
TOTAL_AMT = 0
TOTAL_COST = 0
TOTAL_ITEM = 0
do form FORM_INV LINKED
READ EVENT
*****

SO.....i need to make a .prg for call up a FORM first, do i right !!??