Monument Vandalism? Or Research?

Returning from the 151st GAC Gettysburg reenactment, before leaving town for another year I decided to pay a visit to the real battlefield and the Pennsylvania monument. To pay my respects to those real men who laid down their lives, for they are of course the reason we are here.  I didn't have any trouble finding the 42nd PA "Bucktail" infantry's list of names, as the state regiments are all numbered and spaced around the base of the monument in numerical order. I paused to take a picture so I'd have all the names for reference.

Sure enough, I found it...but what's this??

In company D, middle row, there is a name missing. It looks like somebody chiseled it off.

Wild ideas entered my head. Was it vandalism? An old personal vendetta? An example of Damnatio Memoria?

I was puzzled at this as I drove home, until another historian explained. Over the years, errors have been found in the records. So the park has been quietly removing some names of people who were not at the battle of Gettysburg, and adding others who were not listed but were actually there.  So if a name is up there in error, it's scratched off. If a name should be up there but isn't...do they put new bronze letters on? How do they stick them up there, with superglue?

Anyway, mystery solved. This guy wasn't at Gettysburg, so his name was taken off.

Whenever you see this on a national monument, it's usually that way for a good reason.