Armor Upgrades Work Properly

[XViper]

Sorry for the necro post, but I can't seem to find an accurate answer anywhere.

There's a few threads that explain the actual values of each armour upgrade, however the main thing I can't determine is this.

Is the first value of "armour_ug_levels" used for anything other than a reference point?

So we know the armour values are:
1 = +4
2 = +6
3 = +7
4 = +8
5 = +10
6 = +11


So if a unit had

armour_ug_levels 0,1,2,3

It would get +4 on the first upgrade.
Followed by +6(+2) and +7(+1)

However if a unit had
armour_ug_levels 5,6

Would it get +10 to its base instantly?
Or would this just determine that it's first upgrade would be +11?

Essentially, in the case the first value is NOT 0, is it's underlying value actually applied?
It seems somewhat illogical to be yes, as this is an entirely 'hidden' (and extremely significant) armour buff.
If no, then is there any logic to the vanilla EDU having single values for this field?
There are some units with "armour_ug_levels 6". If there is no second value to determine the value of the 'bronze' armour upgrade, what value does the first number provide?

Thanks for your help, and sorry again for the necro.
I'm working on a large mod, and it is an important mechanic to understand for balancing.

[Northstar1989]

@XViper
Sorry to necro, but to both answer your question, and provide further confirmation of how this works...

The armor levels simply replace the armor levels, they DON'T add to the base levels. I.e. a unit that starts with Padded Armor (base 4 armor, like Italian Spear Militia) and then gets an armor upgrade to Light Mail (base 6 armor) will now have 6 armor, NOT 4.

Try taking units starting with padded armor, upgraded to Light Mail, and units starting unarmored, upgraded to Heavy Mail, and you'll see the ones with 3 upgrades be more resistant to arrows, and win melee with units which are otherwise identical: which wouldn't hold true if the base 4 units got +6 to armor instead of it overwriting the 4 with 6.

I.e. Italian Militia with 3 upgrades (Heavy Mail, starts unarmored) beat Italian Spear Militia with 1 upgrade (Light Mail, starts with Padded) more often in melee (as armor levels only differ by 1, and Spear Militia have longer spears but identical attack/mental stats, the contest is very close and a bit random...)

If the bonuses were additive, you would expect the Italian Spear Militia in Light Mail to win by a mile (10 armor vs. 7) instead of barely losing (6 vs. 7).

Similarly, Italian Spear Militia with 1 armor upgrade (6 Armor) are pretty even with un-upgraded Armored Sergeants (Light Mail, should probably 6 Armor though the unit card states 5 Armor), they don't wipe the floor with them like they would if it were 10 armor vs. 5 or 6.

TLDR: Armor upgrades simply REPLACE base armor rating for sure.