Quick follow-up to confirm that the solution proposed in the previous post seems to work as expected. Google takes its time, but after some weeks it correctly removes from search results all item pages that were shown on sites they don’t belong to. See screenshot from Google’s search console:
(the small numer of pages with errors is caused by an unrelated issue in a theme that I have just fixed).
This seems to be a great improvement for the user experience in the real world, as many users reached our archive via Google searches that led them to the right item on the wrong site, leading to some confusion.
So I feel this may be the preferred solution for many who:
- make generous use of cross references between items
- have multiple sites where it would be odd to see items that are not explicitly associatd with them
Finally, people who read this thread may be interested in the discussion about the persistent identifier module apparently under development, and perhaps, depending on their scenario, consider the relevance of the canonical tag in that context.