So it's link to new tech? Well, that's good to know
As i'm asking newby question, i have another one about the "aid" promotion. Let's say i have a warrior on the same tile as 2 guy with bow. Do this warrior have only one time the bonus of the ranged aid, or do it stack?
This one took a little wrangling, but I think i see what you are asking.
First, there are different levels of promotion aid. A unit will only have one level of a promotion aid per type so he can have Ranged Aid I, or Ranged Aid II, but not both. The level of aid is determined by the amount of the type of aid's base power (so 2x archers = 2x3=6 power), divided by the amount of the units base power (warrior = 2), so that would be 6/2=3. So level III aid. (Which is the max, there is no level IV aid. Well, there's the fort one but that's different.).
Note it is base power it is based off of, not the stated power level, I made the archers take 50% damage so they were only 1.5 power to test if this would lower the aid, and it did not.
Except that for some reason my calculations fall apart when I have a single longbowman and an archer on a tile and the archer gets Ranged Aid III even though that should only be 2.33, and not 3.

But it's a good rule of thumb at least!

Maybe difference in tech levels of the units do something? I sadly cannot read the XML well enough to know if I am even looking in the right place to start reading the code.
I'm asking as, if i select the whole pack the icon as a number, but if i select him alone it doesn't, so i'm not sure...
I just did a test with world builder to see if I can see what you are talking about. I think what you were seeing is this: You select the warrior alone, you see he has Ranged Aid III, a single grey promotion box. But if you were to select all 3 units (1 warrior, 2 archers), you will now see three promotions - Assault Aid I (2), Ranged Aid I (2), and Ranged Aid III. This is because when multiple units are selected, it shows all the promotions held by all units,
and the number of units that have that promotion. So in this case, each of the two archers is getting Assault Aid I, and Ranged Aid I, (the archers only count the other archer, not themselves so 3/3=1).
I'm not exactly what the bottom ratio is for a single level of aid, in this example the Archers still were getting Assault Aid I even though 2/3 =0.66, but a Longbowman with 2/7 = 0.29, does not get the Assault Aid 1.
Darkphoenix: thanks for all the tips, but i knew that already ^^
My main problem is that i'm playing the peaceful way, never starting a war, building very few army.. and even on noble setting, it's hard to survive this way
Thanks for the answer
Yeah, it's sad, the only "peaceful" games I have been able to play on higher levels have been Austronesia and England, having your cities not be attackable by the AI except by sea really lowers their aggressiveness towards you. Without expanding a lot, it's hard to reach that level of power needed to dissuade your neighbors from attacking. And one you have that power, why, that civ's city looks so nice with that luxury good you don't have and he's being a jerk and not wanting to trade it, so let's just take that ONE city and oops I conquered the entire continent again.
