Exactly. The US uses shear size as a boundary to entry into the bases. I learned this after reading about the German family who perished in Death Valley and the

Exactly. The US uses shear size as a boundary to entry into the bases. I learned this after reading about the German family who perished in Death Valley and their perilous walk to find help at the nearby military base which proved fruitless. They were looking for a fence and guard towers not realizing they were walking further from help.