User blog comment:Emlightened/BIG FOOT is SMALLER than FISH NUMBER 7/@comment-5529393-20161225093559

On a more serious note, the main selling point of the strength of FOOT was that, by quantifying over \(V_{\text{Ord}+1}\), you can define a truth predicate for \(V_{\text{Ord}}\), which is equivalent to a truth predicate for \(V\). So each subsequent class gets you a truth predicate for the previous class. To define \(FOST_5\) you just need to go out to \(V_{\text{Ord}+5}\).