The Church Music Association of America has posted the 1961 GRADUALE ROMANUM online, and this book is a tremendous treasure for Church musicians. Looking at some of the pages, one might be led to believe that some pages were, perhaps, vandalized:

However, those who have watched these seven videos will have a different opinion. The “vandalism” was merely marking the mysterious “Vatican white notes” (as Dr. Joseph Lenards called them).

(click here) Talk on the Vatican “blank spaces” • given at Colloquium XX

“Reverse-vandalism” happens in the “pure Vaticana” books by folks like Fr. X. Mathias and Dr. Peter Wagner. There, people mark the Solesmes holds . . .

Vandalism is not always a bad thing. Josquin des Prez supposedly vandalized a pew in St. Peters (writing “Josquin was here”) and this was of infinite interest to scholars when this pew was discovered a few years back.