Canon EOS 5Ds Instruction Manual page 431

<A> Mode Settings and Display Conditions
You can also set Custom Quick Control and display the Custom Quick
Control screen in the <A> mode.
However, functions such as [Expo.comp./AEB] that are not displayed
on the menu screen for <A> mode will not appear on the Custom
Quick Control screen. Also, [ISO speed] and other functions that
cannot be set with the Quick Control screen in the <A> mode will be
grayed out.
Not displayed
Exposure compensation/AEB, Flash exposure compensation, White
balance shift/bracketing, Custom Controls, External Speedlite
control, Highlight tone priority
Grayed out (not settable with the Quick Control screen)
Shutter speed, Aperture, ISO speed, Picture Style, White balance,
Auto Lighting Optimizer, AF operation, AF point selection, Metering
mode
Custom Quick Control
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