What Coinfrog and E&V said..
Still, filled date numbers aren't exactly ho-hum common either..
I for one think they're neat and do save better examples..
As far as Lincoln cents go, both filled 5s & 9s and the BIE error are called die
chips.. However, by definition an area < 1sq mm is considered a die chip while
an area > 4sq mm is considered a die break.. What lay in-between is a grey area..
Swamp