capacity
The nominal holding volume of the EMPTY vessel — how much a drinking or pouring vessel can hold (a 300ml mug, a 350ml glass, a 500ml-1L water bottle, a 1.8L jug), stated in millilitres or litres. It is the size of the empty durable good sold empty, NEVER the contents-as-sold: that is `net_content` (the FMCG fill of a product whose contents are the thing bought, e.g. a 500ml bottle OF a drink). The two are different facts on different products, which is why capacity homes on Drinkware (the durable-vessel branch) and is not forced onto root Product. It is the shared, family-level size slot for every drinking/pouring vessel, so it factors up to Drinkware rather than being re-stated per leaf; a bottle's 24oz-vs-32oz choice is a genuine size selection (concern measurement, axis-eligible).
Capacity is a measured figure, given in liters.
It belongs to measurement — its measurable, physical facts.