Object Modifiers (or OMODs) are modifications applied to a base item. These include Legendary item effects, Weapon and Armor Mods, Armor piece variants such as Sturdy or Heavy, and so forth. Some of these modifiers are attached in game, such as when a Legendary item spawns, or when you attach an armor mod at a workbench. However many of these modifiers can only be added or removed via the console.