Simple armor question

[AMF]

Ok, I've been able to avoid figuring this out for a long time, but I must now ask what is probably a simple question. I looked through the FAQ, and didn't find the answer (but I'm probably looking in the wrong place).

How does armor that automatically dismisses a certain amount of damage work in the aggregate?

For example, Race A has weapons that do X damage. Race B has armor that automatically deflects/abosrbs/dismisses X+10 damage.

When I fire at Race B ships, do all their armor stack against all the damage of my single volley? or does it do it on a shot by shot basis?

For example, if race A ships hit a Race B ship with ten shots, for a total of 10X damage, and race B ship has 5 armor to deflect a total of 5X+50, does the game compare the totals done by Race A to the total absorbed by Race B and apply any extra as damage that gets through?

Or, is each shot by Race A deflected automatically, since it is examined in isolation?

I appreciate any help understanding this admittedly simple issue.

Thanks,

Alarik