Jackolantern
Registered Users (C)
Mathematical calculation could easily be interpreted as (entry date - exit date) by an IO.
If USCIS leaves it to individual IOs to decide that, that means there are inconsistent interpretations of it being applied by different IOs, and the court won't accept that for a mathematical rule. With USCIS being unable to demonstrate a consistent operating procedure that interprets it one way or the other, the courts will hold them to their published instruction (in the absence of overriding law/precedent/etc.).