How poison works exactly?

[tinkthank]

I've seen conflicting information here in my searches, so I will try to ask very explicitly.
There seems to be weak, strong, and death poisons, perhaps there are others. But all I can see when a unit with a poison weapon strikes another is a little green bar underneath the wounded unit.
If this is understood analogously to the bars of fatigue and HP, the unit would be fully poisoned when it extends completely to the right. Yet I am unsure what this actually means, since one can see completely "greened" units up and about.

So does "strong, weak or death" simply have an effect on what happens after the green bar is fully extended, or the rate or intensity in which the green bar extends, or both?

[Wauthan]

As far as I can tell, after some madcap Toxic Avenger campaigns, the green bar indicates that amount of HP that will be lost due to poisoning. A full bar means that the unit is doomed and will die sooner or later that battle. The "sooner or later" depends on the strength of the poison. I'm sure you've gone up against tritons and lost a bunch of units all at once as the battle ends. That's what happens when a unit gets hit by numerous blows from weak poison. Compare that to a Wyrm Pretender that usually drops an enemy in one hit, or it dies the next round. That's death poison at work.

Things can get pretty confusing if you mix a lot of different poison sources in a battle. Units drop very randomly indeed so there's surely a number of dice involved (most likely 2d6+x where x is the strength of the poison).