Canon EOS-1D X Mark III Advanced User's Manual page 851

Add IPTC information
Registering IPTC (International Press Telecommunications Council) information to the
camera from the EOS application EOS Utility enables you to record (add) this information to
JPEG/HEIF/RAW still photos at the time of shooting. This is helpful in file management
and other tasks using the IPTC information.
For instructions on registering IPTC information to the camera and details on the
information you can register, refer to the EOS Utility Instruction Manual.
OFF: Disable
ON: Enable
Caution
IPTC information is not added when you record movies.
Note
During playback, you can check whether IPTC information was added.
You can use Digital Photo Professional (EOS software) to check IPTC information
in images.
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