qualifier token a chosen word

filtration basis

Whether a filtration rating is quoted nominal, absolute or as a beta ratio. A qualifier of `filtration_rating` and not an optional footnote: Baldwin's BF7633 at 4 microns ABSOLUTE and WIX's 33390 at 10 microns NOMINAL are not comparable numbers, and sorting them as bare lengths returns a wrong answer on real parts.

Filtration basis is answered with one word chosen from the filtration bases list — the same word shared across every product that uses it.

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

It is answered inside every filtration 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: Filtration bases — the vocabulary its answers are drawn from.
qualifier of: filtration rating — one per statement — it has meaning only inside that host's statement.

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