· What does the serial number represent?
For Mark 1 players, the serial number is just a sequential unit number. For instance, 00148 would be the 148th Mark 1 player made.
For the Mark 2 and Rio Car players, the serial number is in the format of MMYYNNNNN. So a player number 090000523 would be month 09 (Sept.) of year 00 (2000), serial number 00523.
Note that the initial zero is sometimes dropped, so, for example, 090000523 might be printed as 90000523.
By the way, if you're having trouble locating the serial number sticker for your player, don't forget to peek on the bottom (some players have the serial number on the bottom). It can also be found in the "About" screen from the player's main menu.