I am describing a problem regarding locations positioned next to each other where blocks are placed. For a given layout the locations next to blocks are unusable and in the next step no block might be placed here. For example, in the layout:
The first, fourth and sixth locations cannot be used later. I am looking for a word to describe it. So far i have unusable, or maybe dead space. Is there a better word for this? Thanks in advance!
Example sentence: In the layout above there are 3 ___. In another layout there is one __ less.