Question about DoT

[TheVampire100]

I get how the basic work. It hits, it has a chance to apply the effect (or in some cases does tis alwayws) and the effect comes in play every second for the amount of seconds stated int he duration. So Viper Strike does 25 DPS but lasts only 2 seconds, making it 50 damage (plus the 25 for the inital shot).

The file states it does not stack, which makes sense but what exactly does not stack? The buff itself, so another hit refreshes the duration? or does it not refresh the duration and the effect does not applied again?
What about other DoT systems? Do they add their individual DoT effects or does only the last DoT effect applied count?
Does poison DoT and dire DoT behave differently? Can you apply fire and poison at the same time on an enemy but not add multiple poisons or multiple fires?

[Ayrix]

do_not_stack (bool, optional)
only causes it to not-stack with other modifiers with the do_not_stack flag
if an effect is being copied to an entity, and that entity has another modifier of the same type (and related damage type, etc), and with this flag, then if this modifier has >= the duration and >= the magnitude it will replace the other modifier, otherwise it won't copy over

So non-stacking DoTs will replace other non-stacking DoTs (of the same damage type) only if they are higher damage and last longer.

[TheVampire100]

Thanks, this helps me a lot. So now I know that I don't have to mix multiple DoT of the same time but can mix fire and poison.
This can save me a lot of money.

[Hearteater]

Does "another modifier of the same type" mean that two fire DOTs with do_not_stack="true" would still stack if they came from different modifiers?