It was easy to assign ID letters to the files in each of my 4/3 E5 cameras. Not so with the E-M5 cameras. They are set to keep numbering without starting over and that was easy to set. For batch processing purposes I need to have each camera's file number to include a LETTER such as X or Z at the beginning of the number. I have followed the manual's instructions several times but with no success. I can see the included letter in the menu but not in the file number when exported. Ideas?