Canon EOS 5D MARK IV Instruction Manual page 479

Specifying All Images in a Folder or on a Card
You can specify all the images in a folder or on a card at once.
RAW images and movies cannot be specified.
Do not specify images already specified for a photobook in another
camera for another photobook with this camera. The photobook settings
may be overwritten.
p Specifying Images for a Photobook
When [x1: Photobook Set-up] is set
to [All images in folder] or [All images
on card], all the images in the folder or
on the card will be specified.
To clear your selections, select [Clear all
in folder] or [Clear all on card].
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