One canonical URL per subject

One canonical URL per subject is check B5 in the fifteen-point audit. Each subject has a single canonical URL, and near-duplicates point at it rather than competing.

What counts as evidence

The canonical link we parsed and the URLs that resolve to the same content.

How to fix it

Pick the canonical form (with or without trailing slash, www or not), redirect the others permanently, and use it everywhere.

Where this sits

B is the group: accessibility, comprehension, or extractability. The groups run in order — a crawler that cannot reach the page never reaches the reading checks — so fix the earliest failing group first. The full definition of all fifteen items is in the standard.