Canon EOS 5Ds Instruction Manual page 137

Lens Serial Number
In step 3, if " * " appears in front of the 10-digit lens serial
number, you can register only one unit of the same lens model.
Even if you enter the serial number, " * " will remain displayed.
The serial number on the lens may differ from the serial number
displayed on the screen in step 3. This is not a malfunction.
If the lens serial number includes letters, enter only the numbers.
If the lens serial number is eleven digits or longer, enter only the last
ten digits.
The location of the serial number varies depending on the lens.
Some lenses may not have a serial number inscribed. To register a
lens that has no serial number inscribed, enter any serial number.
If [Adjust by lens] is selected and an Extender is used, the adjustment
will be registered for the lens and Extender combination.
If 40 lenses have already been registered, a message will appear. After
you select a lens whose registration is to be erased (overwritten), you
can register another lens.
3 Fine Adjustment of AF's Point of FocusN
Entering the Serial Number
Select the digit to be entered, then
press <0> so <r> is displayed.
Enter the number, then press <0>.
After entering all the digits, select
[OK].
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