The clarification reads
"Count the number of hexes between the higher unit and the obstacle; this is the number of hexes in a straight line behind obstacle which cannot be seen."
It isn't strictly speaking between as that would exclude the obstacle a better wording would be count the range in hexes from the higher unit to the obstacle.
Luckily the Example is correct but if it isn't read then the blind hexes will be one short.
"Count the number of hexes between the higher unit and the obstacle; this is the number of hexes in a straight line behind obstacle which cannot be seen."
It isn't strictly speaking between as that would exclude the obstacle a better wording would be count the range in hexes from the higher unit to the obstacle.
Luckily the Example is correct but if it isn't read then the blind hexes will be one short.