On pages 422-423 of BWG, there are Obstacles to maneuver based on weather, terrain and light.
So, if you have fog on the battlefield (+2 Ob to maneuver), and your opponent gets 3 successes on whatever maneuver they attempt, is your Obstacle 5?
What if both teams fail their obstacle due to terrain, weather and light? Do you compare successes to see who won, but the winner has no margin of success for extra actions?
More simply: what are the Obstacle modifiers to Maneuver in Range and Cover for?