price valid from
When a stated price begins to hold — the start of its validity window: a pricelist's effective date, a sale window's start. A qualifier of a price host (sale_price, list_price or tier_price), bound to ONE price statement: a real pricelist is a dated document and its window lives on each of its rows — this row's window is nonsense on any other row, so the date travels with the amount it scopes. A windowed list price is still the unconditional ASKING price — the window scopes WHEN it holds, not who gets it; the promotional reduction bundle (compare-at, promo type, eligibility) stays sale_price's. Held as a date literal (LiteralDate); the realised dates are the data layer's rows (L1). The corpus's sale_price_effective_date start; schema.org validFrom.
Price valid from is free text, written for one product alone and never shared as a category.
It is a qualifier of tier price — it has meaning only inside a tier price statement, one per statement, never on its own. It belongs with tier price to pricing — what it costs.
It is answered inside every tier price statement, not as a standalone question on a kind.
Answered inside every tier price statement — not a standalone slot on any kind.