Sales of balance hdb flat -what is included and what is not ?

I know when come to bto , one can have the option to choose if he/she want the flooring and door to be done. and if this is done at the time when the owner move in, the owner can save a significant amount of cash on that. what about sales of balance ? does it have that option when selecting sales of balance ? if there are no option , at which stage of the procedure will u be notified if the flooring and door are included ?