Errors or varieties do not spontaneously occur, they have to be a result of the minting process before the coin has finished being struck and released to a bin. From that point on, it is post minting damage. If a person has a very good grasp of the processes that this involves, the forces, participants, physical and structural limitations of the metals and forces acting on the coin-to-be, can account for everything; except for intentional acts of man such as intentionally forcing an error for personal and financial gain, such as how a dime planchet can get into the cent process. So, no, not everything has to be in a book, but the problem is that many never read a book on the minting process, so they have a problem when someone says PMD. If you do have such knowledge, please tell non-cents how you expect that it occurred in the mint rather than expecting him to find an answer you accept. I know that he has read such books, and I agree with PMD, which on a circulated cent should be the working hypothesis until proven false. IMO. Jim