Canon EOS 1DS MARK II 9443A009 Instruction Manual (en)

The file numbering continues in sequence even after you replace the 
memory card. This prevents images from having the same file number, 
so image management with a personal computer is easier. 
This creates a new folder automatically and starts the file numbering 
from XXXX0001. Subsequent images you capture are stored in this 
new folder. The file numbering method (auto reset or continuous 
numbering) will be the one that was set before forced reset.
Continuous Numbering
Forced reset (M-Reset)
Memory card 1
Memory card 1
Memory card 2
File numbering after 
changing the folder
File numbering after replacing 
the memory card
Even if the memory card still has space, shooting is not possible beyond 
file number 9999. If this happens, follow the instructions on the LCD 
monitor and hold down the <
> button and turn the <
> dial to 
select [OK]. A new folder will be created and you can continue shooting. 
To prevent any interruption in shooting, set the file numbering method to 
[M-Reset] beforehand. 
If the memory card in use has a DCIM folder, the file numbering might 
continue from the last image saved in the folder. 
File names
A file name is assigned automatically to each 
image you capture. The file name consists of a 
unique, four-character camera code preset at 
the factory and a file number assigned 
automatically. The camera code cannot be