Combat bonuses

Does anyone know how the mount_effects are used in the game?
Peltasts have a mount_effect of 6 against elephants and chariots, does this mean that they get their attack is increased by 6?
If you enter a negative mount_effect (like horses against camels) can the final attack factor be made below zero?
I want to make peasants really bad against cavalry. I once attacked a group of peasants with heavy cavalry. 240 peasants against 108 horses, I lost about 30 horses. That doesn't make much sense to me, heavy cavalry should trample a group of peasants.

wow... ...i've never had that happen.
did you simply run them in and have fight like that or did you have them do hit and fades till they were dead.

(i prefer hit and fades when i use cav. agianst light infantry, i believe it's more effective)

I charged them head on, heavy cavalry should be able to just run over light infantry