iwc INGENIEUR PERPETUAL CALENDAR DIGITAL DATE-MONTH Operating Instructions Manual page 8

"L". "L" stands for "leap year". If the current year is a leap year
(i.e. the year is divisible by 4 – e.g. 2016, 2020), you must
adjust the calendar so that the leap year display shows "L".
"1" corresponds to the first year after a leap year, "2" to the
second and "3" to the third. Once set correctly, the perpetual
calendar will automatically show the correct date at all times.
You do not need to do anything until 1 March 2100 when
you must manually move the calendar forwards by 1 day.
Although 2100 is divisible by 4, it is not a leap year accord­
ing to the Gregorian calendar.
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Warning:
In order to protect the watch from the ingress of water, the
crown must always be in position X (screwed in) and should
only be pulled out to position 1 or 2 when setting the watch.
READING THE TIME IN THE DARK
Both the dial and the hour and minute hands of your watch
have luminescent elements that allow you to read the time
effortlessly, even in total darkness.
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