I used to keep three years worth of client info in a file until it headed to dead storage.  To conserve a little on filing cabinet space, I revised that to two years until a new file is created.  As long as a name is on the file that can be read by a human being, I'm not sure why folks want to get picky on the format.  But then again, I'm old and don't want to spend a chunk of my remaining years fussing over names on folders.