Canon EOS 5D Mark III Instruction Manual page 238

3 Setting the Time Code
Regardless of the [Movie rec count] setting, the time code will always be
recorded to the movie file.
Movie Playback Count
You can select what to display on the movie playback screen.
[Rec time] : Displays the recording time and playback time during
[Time code] : Displays the time code during movie playback.
With [Time code] set:
During movie shooting
If you change the setting for either [Movie play count] in [z5 (movie):

Time code] or for [x3: Movie play count], the other setting will also
change automatically.
"Frames" are not displayed during movie shooting and movie playback.

Drop Frame
If the frame rate setting is 6 (29.97fps) or 8 (59.94fps), the time
code's frame count causes a discrepancy between the actual time and
time code. This discrepancy can be corrected automatically. This
correction function is called drop frame.
[Enable] : The discrepancy is corrected automatically by skipping
time code numbers.
[Disable] : The discrepancy is not corrected.
When the frame rate is set to 4 (23.976fps), 5 (25.00fps), or 7 (50.00fps),
the drop frame function does not take effect. (If 4 is set or [53: Video system]
is set to [PAL], [Drop frame] option will not be displayed.)
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movie playback.
During movie playback