Thank youUS Senate 2008, US Flag Code
This is news to me.
Veteran graves with no US Flags on them on Veteran's Day.
Concord, Massachusetts, for example, removes the flags for a Veteran's Day burning ceremony. Burning old flags is per the US Flag Code. Flying a US Flag on Veteran's Day is also in the US Flag Code.
I haven't been around cemeteries on Veteran's Day. The old cemetery nearby flies the US Flag 24/7/365. Thus, in my world, my mind believes on Veteran's Day a flag will be on veteran's graves, just like Memorial Day, when new flags, I thought, replace the old ones that are later burned.