That {{imposed}} property is part of the simple template. It's only displayed during a disadvantage roll. This is about the simplest form of the template: &{template:simple} {{r1=[[1d20]]}} {{r2=[[1d20]]}} {{disadvantage=1}} {{imposed=Imposed Text}} {{rname=rname}} It's also available in the simple3D template, if you happen to be using that. The disadvantage itself is triggered by the item mod Stealth:Disadvantage If you want to permanently apply disadvantage to another character's rolls, simply add that to the mod section of one of their inventory items. Note that this isn't at all a robust system - adding stealth:advantage or acrobatics:disadvantage will not do anything. Quite why this particular case was singled out and automated I have no idea - RAW, any source of advantage will cancel out the disadvantage, so completely sidestepping the Query setting seems bizarre to me, but - /shrug - I'm not telling other people how to play. It also seems to be hard-coded to {{imposed=Heavy Armor}}. At least, applying the disadvantage:stealth mod to a weapon still says "Heavy Armor" when I tested it, despite that text not appearing anywhere in the weapon attributes. tldr - this is hard-coded into the sheetworkers & roll template, specifically for heavy armor (from what I can tell). There's nothing here useful to API scripters - they already had the ability to scan the inventory for equipped heavy armor if they so wished. So.... clear as mud? :)
