See also page

Calculate the decay of an itemDamage/PEC or DPP is a way to describe the efficiency of an item from a cost/benefit perspective.It should give you more kills per PED, which may be a benefit. There are however uncertanity to the real benefit, and there are occasions where high damage per second (DPS) is more desireable, at least if the DPP is not too far off.

What it gives you is a number telling how much each damage dealt costs using this weapon, and you can add factors like markup on ammunition (relevant for

Shrapnel/

Universal Ammo and

Explosive Projectiles) and limited (L) attachments and weapons, and also enhancers.

Factors as overkill (dealing more damage than the mobs current hitpoints, as weapon deals 100, but mob only have 10), mob regeneration etc. should probably be described elsewhere.

The Entropedia damage per pec is Damage/(Ammo cost + Decay cost), where damage is Effective damage.

MindArk gives us a DPP number, which seems to be based on max damage. It can probably be converted to Entropedia DPP multiplying it by 0.695 (Thanks to Svarog) - this is likely correct, but not tested on all the weapons with MA DPP, so corrections are very welcome.