qualifier token a chosen word

heat range scale

also called whose heat scale

WHOSE heat-rating scale the number is on. It is required on every heat-range statement and it is not a formality: the four scales in the trade do not merely start in different places, TWO OF THEM COUNT THE OPPOSITE WAY. NGK's catalogue prints "Hot type" against 2 and "Cold type" against 10; Bosch's prints "Hot" at the top of a column that begins at 13 and "Cold" at the bottom where it ends at 06. So a bare "6" means a fairly cold plug from NGK and a fairly hot one from Bosch, and Denso's numbers (9 to 31) do not overlap either. Without this qualifier the pool would let a shelf sort NGK 6 against Bosch 6 against Denso 20 and return a ranking that is not merely imprecise but backwards. The b154 precedent exactly: a `viscosity_grade` may not stand without its `grading_scale`, because an 80W-90 gear oil and an SAE 50 engine oil are about equally thick. Note this is the MAKER OF THE SCALE, which for a plug in an OEM box need not be the maker of the plug — Toyota's 90919-01210 is a Denso plug and carries Denso's rating.

Heat range scale is answered with one word chosen from the heat range scales list — the same word shared across every product that uses it.

It is a qualifier of heat rating — it has meaning only inside a heat rating statement, never on its own. It belongs with heat rating to measurement — its measurable, physical facts.

It is answered inside every heat rating statement, not as a standalone question on a kind.

answered with: ◇token — a token — a word chosen from a fixed vocabulary, shared and filterable across products.
value domain: Heat range scales — the vocabulary its answers are drawn from.
qualifier of: heat rating — required_one per statement — it has meaning only inside that host's statement.

Answered inside every heat rating statement — not a standalone slot on any kind.