XML structure

When inside main node (Will be loaded globally at all times.)

When inside <level> or <instance> node (Will only be loaded inside your custom level.)

Optimally you want the equipment to only be loaded in the level you need it in.

id

The ID for your equipment. Has to be unique.

based_on

Will base your special equipment on a already existing special equipment.
All tags, parameters and values will carry over, but can be overwritten by specifying them in your xml.

icon

The ID for the icon showing up in the player's inventory. Can technically be any HUD Icon from the hudiconstweakdata.lua.
Alternatively you can also add your own icon.

text_id

The string ID for localization. Overkill usually uses something like hud_equipment_(your equipment id).

Defaults to hud_equipment_(your id) if not specified.

quantity

Amount you get when optaining this equipment.

max_quantity

Maximum amount you can have of this equipment.

transfer_quantity

How much of this equipment gets transfered to other players when disconnecting or going into custody.

avoid_tranfer

Set to true to not transfer equipment to other players when disconnecting or going into custody.
*No, it's not a typo, it actually is misspelled in the tweakdata.