DS-156表的所有空格都要填么？

At the top of DS-156, the instruction says that:

"Please type or print your answers in the space provided below each item"

When I filled out DS-156 online, for certain items like Item 8(Other Surname used) and Item 9(Other First and Middle name used), I simply left them blank, as I only have one Surname and First name.

Now when I'm thinking about the instruction above, I'm a bit concerned. Do blank (unfilled) items matter? Do I have to put N/A on all items not applicable, based on the instruction above?

Thank you for your information!