I dont remember seeing this bookmark before on the briars page

[Aerobane]

I looked today and noticed a change to the book of briars. Seems to be a bookmark with the following words
“Yankee, Kelsey, Mike, Sebastian, Didier, Zerovin” on the cover. Anyone know the significance of this?

[Robert]

When a fragment is solved, those who helped out and find the page are invited by the Book to place their name in it for a time.