Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 164)

2.
Set the image size.
Standard/Auto switch card/Record to multiple
For RAW images, turn the < > dial, and for JPEG images, turn the
< > dial.
Press < > to set it.
Record separately
When [ Record func. ] in [ : Record func+card/folder sel. ] is set
to [ Rec. separately ], turn the < > dial to select [ ] or [ ], then
press < >. Note that recording separately to and is not
available for RAW images.
Select an image size on the screen displayed, then press < >.
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