Terrain effects on the battlefield

[digger1985]

I was wondering how different terrain types affect units on the battlefield (I am not talking about the world map).
It is written in the manual: 'The different terrain affects units in different ways.' (page 31)
Is it only movement affected, so that some unit types are faster than other on different terrain types?
Are combat characteristics affected too? I guess so, since chariots are said to be more effective on the open ground.
If combat characteristics are affected, what is the file in the game folder that describes the effects?
I can see only CombatModifiers.csv but it is unclear how it is used by the game. I assume 9 in the first line is the number of different terrain types, then there are 11 unit types, but I have no clue what the actual unit tables mean.

I was thinking whether auxilia units can be more effective than their swordsmen counterparts of the same tier, and under what conditions the former can be more effective than the latter.
Probably Sabum Qallatum vs Sheridan can be a good example for the early game. However, if it turns out that Khepetj are more effective than Sheridan in the forest (or even the same), I would be happy to learn too.