how to determine if a smartform is printed

good day gurus...

i have develop a print program and a smartform which prints the official receipt. now, what i need this time, is to determine, if the smartform is already printed or not. so what i am thinking is, i have to create a z_table that will store the spool number and the document number once it is printed.

my problem now are the following:

1. what are the tables that are linked to the spool numbers and the document number(belnr).

2. how could i determine if the print button on the smartform is already pressed or not.

thanks a lot for your help.