Language cluster: the set of addresses that are each other alternates
A language cluster is a set of addresses that each declare the others as alternates. Maintaining one tells a search engine that near-identical pages are deliberate versions rather than duplicates, which is worth real traffic to a company selling in several markets. As of 2026-09-22.
| State | What the markup shows | What a reader should conclude |
|---|---|---|
| Complete | Every address lists every other, including itself | The set is maintained |
| One-way | One address lists others that do not list back | Part of the set may be stale |
| Stale target | An address is listed but redirects or is gone | The declaration outlived the page |
| No cluster | No alternates anywhere | Nothing is claimed, and nothing is ruled out |
Inclusion rule. The states a cluster can be in as seen from the markup alone. Judging which state a vendor is in requires opening the addresses. Order. Complete first, then the failure modes.
1Why a cluster is maintained at all
Several pages saying nearly the same thing in different languages look like duplicate content. A declared cluster tells a search engine they are alternates and that each belongs to a different audience, which stops the engine picking one and ignoring the rest.
That commercial motive is why these declarations are decent evidence. They are maintained because they pay, so they tend to reflect where a vendor is actually selling rather than where it would like to.
2Clusters go stale quietly
A language version gets retired, the declaration stays, and it now points at a redirect or a missing page. Nothing on the surviving pages changes, and a count taken from the markup will include the dead entry.
That is a maintenance failure rather than a false claim, and it is common enough to be worth checking rather than assuming. It is also the main argument for recording the date a count was taken.
3A cluster spanning two domains is a different object
Where a cluster reaches across domains, the pages on the other domain belong to that domain. Whether they are the same company, a licensee or a partner cannot be read from the markup.
This register keeps counts to the host being read for that reason, and prints the cross-domain declarations separately. Two vendors here lose a Chinese alternate that way, and two more lose most of their set.
A definition, not a measurement: no vendor figure appears here that is not also in the register. Both discarded Chinese alternates are recorded on the vendor pages that declare them.
Nearby terms: Locale, Language switcher. The whole vocabulary is at terms; nothing on this page is a claim about a named product.