"What is great about digital publications from WT perspective is that they can delete them once they realise it's old light." -- Skepsis
When I was a proofreader, Bethel, Brooklyn, I remember one of our senior members, Ann Rose, noting textual errors, found in recently published books, on the back fly leaf. That's what we called "errata data."
I don't recall on how wide a scale it was done, but we would take a separate "signature" (folded sheets of paper) with printed corrections and manually glue it into the back of the book.
"Errata data tipped in" means that corrections have been inserted.
We've come a long way, Baby!