One vocabulary for every knob catalogue in the SDK and its plugins, so a UI or an agent that learned one catalogue can read the other.
toggle: true/false, e.g. whether an overlay is drawn.factor: a multiplier over what the style already does (1 = unchanged).number: an absolute number with a range.color: a CSS colour string.enum: one of the knob's options.colors: a list of colours, each a CSS colour string or one of the knob's options — names
the module resolves to colours, such as styling knob ids. An empty list is the knob's default.
The kind of value a display knob takes.