Fluid Topics generates Related links between documents written in the same language.
Documents written in the same language but with different regional designators (for example, xml:lang="en-US" and xml:lang="en-GB") cannot trigger Related links even though they share the same metadata.
Documents that are written in English but for which no regional designator has been defined automatically receive the regional designator en-US. In a similar way, Fluid Topics automatically assigns a default language to all documents for which no language has been defined. Documents impacted by these mechanisms can trigger Related links.