The natural coupling in a file with a uniform grid and a list of small volumes
is that the grid indexes the volumes. Tested by spatial agreement, it does not.
Test 1: every u16 in a cell's 32-byte payload, tried as a section-1 index and
checked for its centre lying inside the referencing cell. Every field sits at
the 0.138% random-control rate.
Test 2: every float triple in the payload, checked for lying inside its own
cell. 0.15-0.81%, also chance.
Recorded a worthless number from the same run rather than dropping it: those
triples lie inside the object's BOUNDING BOX in 100.00% at five different
offsets. The bbox spans the whole 500 km map so any mid-range triple passes, and
overlapping windows at +0 and +4 both scoring 100% is the tell -- a real field
would not survive a four-byte shift. Third time in this investigation that a
containment test against something large has produced a meaningless 100%.
Incidental and real: u32 slots at +0, +8 and +12 are below 0x10000 in 100% of
payload records while +4/+16/+20/+24 are in 11% and +28 never, so the record has
three index-shaped fields and four wide ones.
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