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properties /sale price

qualifier number + unit a measured amount

compare-at price

The strike-through reference amount a conditional sale price is shown against ($40, struck through, beside the $30 sale). A qualifier of the sale-price host, bound to one sale-price statement, as a numeral on the same currency unit. Its magnitude is realised; the currency is the governed unit. The discount percentage a surface prints is presentation derived from (compare-at − sale), never stored.

Compare-at price is a price, given as an amount in a currency such as USD or EUR.

It is a qualifier of sale price — it has meaning only inside a sale price statement, one per statement, never on its own. It belongs with sale price to pricing — what it costs.

It is answered inside every sale price statement, not as a standalone question on a kind.

answered with
number + unit — a number paired with a unit drawn from an exhaustive unit vocabulary.
value domain
Currencies — the vocabulary its answers are drawn from.
qualifier of
sale price — one per statement — it has meaning only inside that host's statement.

Answered inside every sale price statement — not a standalone slot on any kind.