The Paligo connector already supported cross-book links using Paligo data-origin-id identifier (which translates into ft:baseId in Fluid Topics). In partnership with Paligo, we have added support for cross-book links using Paligo fork-id (which translates into ft:originId in Fluid Topics).
What is the difference? Both systems have two identifiers to identify a topic:
A common identifier for the topic whatever its use,
A specific identifier for the topic when used in a specific publication.
For example, if a topic is used in multiple variants of the same document (v1, v2, v3, …), it will have one common identifier and multiple specific identifiers (one for each variant).
When creating a link to a topic in another document, we wanted to offer the user the ability to choose between these two identifiers:
If the link targets a specific version, it should use the fork-id in Paligo.
If the link does not know which version to target, then it should use the data-origin-id in Paligo. In that case, Fluid Topics shows a preview of the content with a selector of the desired variant.