How it happens
A backpack is 48 litres in 2025 and 45 litres from 2026. Your page now says 45. Four retailer listings, three reviews and a comparison site still say 48. The model has seven sources for one value and one source for the other, and no sentence anywhere saying that one replaced the other.
What makes the change legible
- State it. "45 litres from 2026; the 2025 version was 48 litres." The old
value in context is a fact about history; the old value alone is a contradiction.
- Date it. A value without a date cannot be ordered against the others.
- Keep the old value on record — superseded, not deleted. Deleting it
leaves only third-party pages to describe the old version, uncorrected.
- Update the identifiers if the revision has a new GTIN.
The checklist for the week a product changes is at /checklists/when-a-product-changes.
How to tell if it worked
Ask the same questions in several models two and four weeks later and record which version each answer describes, with the model name and the date. Without that record you cannot tell a corrected answer from a lucky one — see /evidence.