what is inside my 6?

I wanna say Die "Cud" but I was told they include the rim of the coin. so lets see what others say.

"cud"
"An area of a coin struck by a die that has a complete break across part of its surface. A cud may be either a retained cud, where the faulty piece of the die is still in place, or a full cud, where the piece of the die has fallen away. Retained cuds usually have dentil detail if on the edge, while full cuds do not."

from Coin Community Forum Glossary, under Navagation on the Left hand side of site.

Die chip. In order to be a cud, the out part of the rim would need to fall off. This is in the center.