Your manual must be different then mine. My manual says the mark button or spacebar. I havn't played the game since windows took away the DOS shell for DOS game not sure if it was 98 or ME. My trick to get range was if you knew a ship that was 100' high was 6 dashes tall at 6000' It would be 3000' at 12 dashes 1500' at 15 dashes. You were not spot on but it was good enough to get a solution.
I think where I was thinkig of clicking in the scope was because I would mark the dash with my mouse pointer as a reminder since it was easy to count the dashes against the horizon. I didn't have the internet back then so I never downloaded any charts to help me out.
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