Sorry, but I looked through the instructions and the tutorial and could'nt find anything telling me what those numbers mean. As an example 4/1 what does the four mean and the one.
the first is the detection rating vs land, the second vs naval.
It is checked against the hide value of the opponent army. Some bonus to this hide value: +1 in very harsh weather (blizzard), +1 in wilderness. No wonder a regular cant see an indian 10 meters in front of him!
If you have 51% loyalty in your favor in the region, you gain +1 detection point
Hofstadter's Law: "It always takes longer than you expect, even when you take into account Hofstadter's law."