Isabelle's documentation PDFs are regenerated with every new version of Isabelle, even if they seem unchanged for many years. E.g., even the "Old Introduction to Isabelle" (superseded back in 2002) is dated 13 March 2025.
This makes it difficult to keep track of what actually changed or not at each new version.
Is there a changelog for the documentation?
You can look at the version history of the theory file that generates the PDF. There are the NEWS but those typically don't mention changes of documentation explicitly.
Last updated: Aug 13 2025 at 08:30 UTC