Canon EOS R5 Mark II Advanced User's Manual page 464

HDMI
Time code
Time codes can be added to movies as you record them to an external device via HDMI.
Off
No time code is added to HDMI video output.
On
Time codes are added to HDMI video output. When [On] is set, [Rec Command] is
displayed.
Rec Command
For HDMI video output recorded by an external device, you can synchronize recording to
when you start and stop recording movies on the camera.
Off
Recording is started and stopped by the external device.
On
Recording by an external device is synchronized to starting/stopping recording on the
camera.
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