properties /facet

What carrier the product is built on — mineral oil, a semi-synthetic blend, a full synthetic, ethylene or propylene glycol, a glycol ether, or silicone. One question, 'what is the fluid itself made of', answered the way each corner of the trade answers it: for an engine oil the maker publishes a degree of refinement, for a coolant or a brake fluid a chemical family. CARDINALITY MANY, because a product really can be asked both at once and one sentence proves it: Liqui Moly publishes its DOT 4 as 'a SYNTHETIC brake fluid based on GLYCOL ETHERS, alkyl polyglycols and glycol ether esters', and the same house prints `Base | Polyglycol` as a data row across its DOT 3, DOT 4, SL6 and DOT 5.1 range while selling all of them as synthetic; MOTUL does the same at header level, '100% Synthetic Fluid' on a polyglycol fluid. Under a single-valued slot the pool would have to discard one of two facts the maker published about one product. It is the biggest single merchandising axis on an oil shelf. DISTINCT from the universal `material` (facet, over MaterialTypes): `material` says what an artefact is CONSTRUCTED from — a steel body, a plastic housing, a ceramic element — and MaterialTypes is a vocabulary of construction materials with no notion of a refinement degree; a semi-synthetic blend is not a material an object is made of, it is a statement about how the substance itself was produced. Putting 'mineral oil' into MaterialTypes would make the steel body of a filter and the oil inside it the same kind of statement. Concern measurement, so axis-eligible: mineral and full-synthetic of the same brand are versions a buyer chooses between.