Hello Morimoto San,
It is unspecified it can be either 0 or 1. For example DQ6 is " No toggle " during "Reading within Erase Suspended Sector" . That means in the data in the consecutive bytes you will not see any bit toggling. You just need to look at the other bits DQ7,DQ5 etc. Similarly for the bits which are "N/A" means that you need not worry or check those bits.