NNP

Filled Letter.  A striking error in which a tiny die projection in the center of a letter breaks off, all pieces struck subsequent to this will exhibit the malformed letter due to a greater die cavity. The centers of O and D, the loops of A, P and R, in addition to certain figures, 6, 8, and 9 for example, are most susceptible. The part of the die which creates the center is a tiny projection that is highly susceptible to great metal stress and the possibility of breaking off. When it does separate this creates a cavity, which on the struck piece forms a filled-in letter or figure. An attempt to eliminate this problem is to grind off a portion of this tiny tall projection in the die or negative pattern.  See champs levée.  In describing a filled letter it is sometimes called "solid;" it is better to say filled, as 1930-D Lincoln cent filled D.

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators

COMPILED AND WRITTEN BY D. WAYNE JOHNSON

Roger W. Burdette, Editor