Grain scooped from the bottom and drained on the spoon, the traditional pull. It gives the most Maillard development and the most scorch risk, and it's the thickest a pull can be. The ratio is the grain's own absorption, because drained grain still holds about a litre of liquid per kilogram.
The usual compromise, around 1.5 L/kg.
Liquid only. It's used to raise temperature, not for flavour. With no grain there's no starch to gelatinise and little of the Maillard character a decoction is usually done for.
How much grain comes out with a decoction relative to liquid.