Thank you for the answer.
One detail that i not indicate was what i want do that for... Well, i am implanting Compiere in a Software Company and it became necesary the service order be splited in several invoice thus a service order with, say, 100 man-hour and a total of, say again, 1000 USD be splited in three invoice: one with 300 USD at service start, other with 400 USD at 30 days of the beginning and last with 300 USD at end of service.
Can be done that with the same suggestion that red posted??
how to use Compiere?