Macro selecting multiple items in list box
 

I have a list box which allow multiple items to be selected. A macro later
takes that data and enters it in the desired location a list of 1s and 0s.
When I come back to the same row, I would like the list box to show me what
has already been selected. Is there some way to write to the list box,
causing each item to be selected or unselected as the case may be. Thanks.