Item lots, configured in ItemLotParam, define an item or collection of items that may be granted to the player. Rather than specifying an item directly, most sources of items such as map treasures or event scripts are given an item lot ID instead, which allows them to be more flexible in terms of droprate, number of items given, and other properties.

In order to edit them, use the appropriate param editor for your game.

Item Lot Properties

Each individual item lot can specify up to 8 different items; however, when multiple items are specified, only one of them (or none) will actually be granted. The purpose of listing multiple items is to randomly choose between them, based on the weight given to them. Rather than weights being given as a fixed value such as percentage out of 100, the weight of each item is relative to the total weight of all 8 items. For instance, if an item lot has 3 items each with a weight of 50, the drop rate of each will be 33% because the total weight is 150.

In order to make an item lot always grant a certain item, the weights of the other 7 items simply need to be set to 0, and the weight of the guaranteed item set to any positive value (although typically 100 is used). In order to make an item lot that can grant nothing at all, add an item with a category of -1 and an ID and quantity of 0; if that item is chosen, nothing will be granted.

The cumulative ("cumulate") fields allow additional item lot rolls to increase the odds and eventually guarantee items to be granted. If the item lot is given a cumulateNumFlagId, it will be used as an 8-bit event value to store the number of times that lot was rolled.
Every time after the item lot has been rolled, cumulateLotPoints are added onto the lotItemBasePoints to increase the chances for that item.
If the amount of rolls has exceeded cumulateNumMax, all items with zero cumulateLotPoint (including the "nothing" item) will no longer be included as a possibility, guaranteeing a cumulative item will be granted.

Field Description
lotItemId01-08 The item IDs of the 8 possible items
lotItemCategory01-08 The category of each item (for values, see below)
lotItemBasePoint01-08 The weight of each item for droprate calculation
cumulateLotPoint01-08 Value added onto lotItemBasePoint every time the item lot has been rolled. Uses cumulateNumFlagId
getItemFlagId01-08 Event flags for individual items; how these behave exactly is not currently known
getItemFlagId Event flag set once an item has been granted. The flag is not set if the lot is random and chooses no item. If this flag is set, the itemLot will be skipped
cumulateNumFlagId The initial event flag ID for an 8-bit event value1 that store the number of times this item lot has been rolled. Used with other cumulate fields
cumulateNumMax Maximum amount of itemLot roll attempts before guaranteeing the item drop. Example: a value of 3 would do nothing until AFTER 3 unsuccessful attempts, and would guarantee item drop at attempt #4. Uses cumulateLotPoint
lotItem_Rarity Determines how fancy the glowing treasure effect is; does not affect droprate
lotItemNum01-08 The quantity of each item to give; setting this above 1 for items like weapons and armor will grant a single stacked item rather than two separate ones, which is usually not desirable
enableLuck01-08 Allows item discovery buffs to affect each item's droprate. In DeS and DS1, it reduces odds (usually applied to the "Nothing" LotItem). In BB onwards, it increases odds.
cumulateReset01-08 Whether getting each item will reset the cumulate counter

In Dark Souls 3, ItemLot item categories are a little special:

Item Category Description
-1 Special category used for a chance to not grant an item
0 Weapons (also used as a default value)
268435456 Armor
536870912 Accessories (rings, and in DS3 the covenant badge)
1073741824 Goods (consumables, key items, upgrade materials, etc)

Granting Multiple Items

As mentioned above, each item lot grants at most one item. In order to add multiple items to the same treasure or multiple rolls to one enemy drop, all item lots with sequential IDs will automatically be granted as well. For example, the Sen's Fortress mimic's item lot is set to ID 27800000, which drops the Symbol of Avarice. After attempting to grant that lot, the next ID is checked, in this case 27800001, which does exist and so is granted as well, dropping the Lightning Spear. Then it continutes on to 27800002, but since that lot does not exist, the process ends. Be careful to not accidentally use an ID that directly follows an existing one if you don't intend them to drop together.

Granting different items in New Game+

An ItemLot can have the ClearCount (DS3) or GameClearOffset (ER) field set in order to replace itself with a different ItemLot once the player has reached NG+.

The ItemLot will be replaced with (ClearCount variable times 100.000.000).

For example, if ItemLotParam row 1234 has a ClearCount (or GameClearOffset) value of 2, then it will be replaced by ItemLotParam row 200001234 when the player is in NG+ (if it exists).

There is currently no known way to increment this per NG+ cycle.

Item Lots in Sekiro

In Sekiro, additional conditions such as game progress and the Bell Demon can cause item lots with IDs +10 to +40 to be granted as well.