.cmf and .cem ???

[Duncan]

I have downloaded some scenarios fro CMBB. They have a .cfm extension and won't work on my machine. I have renamed one to .cme and it works. What's the dif?

Dnepre River Crossing. The scenario selection screen says 3 turns. Playing the scenario says 15+ turns. The Blitz say 45 turns. What's up?

Thanks.