Canon EOS 5D Mark III Instruction Manual (en)

 Setting the Image-Recording Quality
A RAW image is raw data output by the image sensor converted to 
digital data. It is recorded to the card as is, and you can select the 
quality as follows: 1, 41, or 61.
A 1 image can be processed with [31: RAW image processing
(p.288) and saved as a JPEG image. (41 and 61 images cannot 
be processed with the camera.) While the RAW image itself does not 
change, you can process the RAW image according to different 
conditions to create any number of JPEG images from it.
With all RAW images, you can use Digital Photo Professional (provided 
software, p.394) to make various adjustments and then generate a 
JPEG, TIFF, etc., image incorporating those adjustments.
About RAW
If you select both RAW and JPEG, the same image will be recorded 
simultaneously to the card in both RAW and JPEG at the image-
recording quality that was set. The two images will be recorded with the 
same file numbers (file extension .JPG for JPEG and .CR2 for RAW).
The image-recording quality icons are as follows: 1 (RAW), 41 
(Medium RAW), 61 (Small RAW), JPEG, 7 (Fine), 8 (Normal), 3 
(Large), 4 (Medium), and 6 (Small).
Commercially-available software may not be able to display RAW images. 
Using the provided software is recommended.