What does f g mean on a penny?

The letters "FG" to the right of the Lincoln Memorial on the reverse of US cents minted since 1959 are the initials of Frank Gasparro, the Chief Engraver of the US Mint and designer of the Lincoln Memorial reverse. He also designed numerous other faces of coins, including the Susan B. Anthony dollar (both obverse and reverse, if memory serves). On the front side the letters are VDB