Thanks coinguy! Being new to coin collecting I had no idea this was a common thing. Now that you've responded I see all sorts of references to the term.

Has anyone ever come across a 1964 dime with a smooth edge and has different dimensions than called for in the original specs. It is 17.21mm in diameter and 1.78mm in thickness. originally I thought it was excessive wear on the edge but the unusual thickness makes me think otherwise. Comments? 1964 ...