Question about Cormack Units

In https://github.com/neurolabusc/Clinical/blob/master/clinical_h2c.m#L41, it says 
```matlab
%e.g. -100..+300
```
but that distance is 400, so shouldn't https://github.com/neurolabusc/Clinical/blob/master/clinical_h2c.m#L41 be 
```matlab
kInterestingMidUnits = 400; %e.g. -100..+300
```
?