The Central Loot NFB Economy (often abbreviated "CLE") is DayZ's unique management system for loot spawning and clean-up. It is a complex system of tags, categories, zones, maximums, minimums, averages, and so on. The CLE dictates exactly how many of each item can be present on a single instance of the game at a time (one server), with important factors like randomization and rarity baked in. These values can be adjusted at any time, without requiring players or servers to install a game update.
In addition to controlling how much of each item is present, it also "cleans up" the map by removing items which have become ruined or which have gone untouched for a set amount of time. This function prevents the game from becoming cluttered with useless items, serves players with a continually refreshed pool of available gear, acts as one method of preventing individual players from having too much influence over the entire server's economy. For more information about how long items stay in place without activity, please see the table below for Persistence.
The first major role of the Central Loot Economy is managing the spawning of loot around Chernarus. In DayZ Standalone rather than having random loot spawn at specific locations around the world, the Central Loot Economy manages every item that can spawn, the amount of the item that can spawn and the locations where the item can spawn. In order to select from the over 10,000 potential spawn locations, every item and building in the game has a set of Category and Location tags that the Central Loot Economy uses to determine which items can spawn at what locations. Additionally, some items have a set of Zones, specific areas on the map, in which they are able to spawn, further increasing the variety of loot around Chernarus.
Once an item's location has been determined, the Central Loot Economy will then randomly determine the condition the item spawns in with and, if applicable, attachments or additional items that spawn on or within the spawning item itself.
Using these tags, zones, conditions, attachments or items within the item along with some additional item spawning stats, the Central Loot Economy spawns loot in places that make sense while still allowing for a wide variety of locations or "variants" of the item, ensuring that players get a fresh but not completely random experience each time they loot a building.
The Category tag is used in both buildings and items. On items, this tag is used to classify the type of item it is. On buildings, this tag is used to determine the types of items that can spawn in or around the building. There are seven different Category tags items and buildings can have.
Almost every item has one Category tag. This tag sets the item's type and is used by the Central Loot Economy to determine which buildings can spawn the item. An item's Category tag, in general, matches up with the type of item it is (i.e. The Cargo Pants have the Clothing Category tag, the Hacksaw has the Tools Category tag). Items without a Category tag can spawn where ever its Location tag(s) will allow it.
Every building that spawns loot has one or more Category tags, generally two or three. These tags are used by the Central Loot Economy to determine which items can spawn in the building. Like items, a building's Category tag(s) match up with the type of building it is (i.e. The Grocery Stand has the Food Category tag, the Garage has the Vehicle Parts Category tag).
The Location tag is used in both buildings and items. On items, the tag is used to determine where this item can spawn. On buildings, this tag is used to roughly classify the type of building it is. There are thirteen different Location tags items and buildings can have.
Almost every item has one or more Location tags, generally two or more. This tag is used by the Central Loot Economy to determine which type of buildings the item can spawn in. An item's Location tag(s), in general, match up with the type of place you would normally find an item like this (e.g. The Ammo Box has the Military Location tag, the Firefighter Axe has the Firefighter Location tag). Items that have no Location tags can, in general, spawn where ever its Category tag will allow it.
Buildings and Items that would normally be found in coastal or fishing areas.
Every building that spawns loot has one or more Location tags. These tags roughly classify the type of building it is. The Location tag does NOT determine where a building is. This tag is used by the Central Loot Economy to determine which items can spawn in the building. A building's Location tag(s) roughly match up with the type of building it is and where you would find it (i.e. The Construction Site has the Industrial Location tag, Deer Stands have the Hunting Location tag).
The Central Loot Economy also allows for a variety of spawning methods and locations, not just in buildings around Chernarus.
Spawning Inside Items
Some items can also spawn with other loot inside of it. Primarily backpacks and clothing, these items can spawn Food and Drink and other small tools. Both the primary item and the items inside of it are managed by the Central Loot Economy and adhere to the categories and locations tags. This means the primary item will not spawn with totally random loot inside of it, rather it spawns with loot that you might normally find in such a location (e.g. A Hiking Backpack will not spawn with an ATOG Scope inside of it).
Spawning With Attachments
In addition to spawning items inside of other items, the Central Loot Economy will also spawn firearms in with a random assortment of attachments or magazines. Firearms will not always spawn with attachments and when they do, it can be one or several attachments. This includes:
Detachable Magazines (with a random amount of ammunition)
Sights & Optics
As of 1.04, weapons with internal magazines like the BK-133 or Mosin 91/30 can not spawn with ammunition.
In addition to being able to spawn within other items, loot can also spawn on or held by the Infected. Able to spawn with a variety of clothing, headwear, vests and backpacks, the Infected can also spawn with items in their inventory. Based on the "type" of Infected it is and where it is at, they can carry everything from food and drink, to tools and ammunition.
Some items, namely fruit, mushrooms and small stones, do not spawn in the same fashion as other items. Instead the Central Loot Economy will randomly spawn these items in certain locations. Apples, plums and pears around their respective trees. Mushrooms in the forests or other dimly lit locations. Stones around and on railroads and along dirt hiking trails.
To better simulate a lived-in world, loot doesn't always spawn in Pristine or brand new condition. Instead, the Central Loot Economy spawns items within a range of conditions. Items can spawn in one of the following conditions:
Items never spawn in Ruined condition.
The second major role of the Central Loot Economy is commonly refered to as Persistence. While Persistence does prevent things like oil barrels and player-made fortifications from despawning, that is only part of what it does. As part of its Persistence System, the Central Loot Economy also manages other "non-persistant" loot that has spawned and performs Item Cleanup where necessary. This aspect of the Persistence System serves to keep fresh loot spawning and prevents the server from getting bogged-down with discarded, ruined or otherwise unused items.
*Note: Item Cleanup/Persistence time does not apply to anything carried by a player. These items will not despawn.
When players refer to an item, object or structure as being "Persistent ", what they mean is the item, object or structure does not despawn or move during a server restart and has a very long Item Cleanup time, or the amount of time before an object is despawned by the Central Loot Economy. There are a couple of exceptions to these rules:
Ruined Items are cleaned up regardless of their Persistence
Vehicles will occasionally move or slide during a server restart depending on its location
The length of time an item, object or structure is in the world before the Central Loot Economy despawns it, varies based on the object itself. If, at any point, the object is interacted with in any way, its Item Cleanup timer will reset. Essentially, Persistent objects that are regularly used or interacted with will never despawn (assuming they do not become ruined or the server is not wiped).
Items or objects that are "non-persistent" are also managed by the Central Loot Economy. "Non-persistent" items will not automatically despawn if walked away from, rather these items just have a much shorter Item Cleanup time and/or may be removed upon a server restart.