IWC Schaffhausen Aquatimer Split Minute Chronograph Mode D'emploi page 23

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Date setting
If a month has fewer than 31 days, you must set the date by hand to the first
day of the following month. To do this, release the screw-in crown and pull it
to position 1. You can now change the date by rotating the crown to the right
(quick setting).
Time setting
Pull the crown to position 2. This will stop the movement. To ensure that the
set time is accurate to the second, it is best to stop the movement as the
seconds hand reaches 60. You can now position the minute hand exactly on
the minute line. To start the seconds hand, push the crown back to position
0. When setting the time, please be aware that the date change always takes
place at midnight (24.00). If this change has already taken place at 12 noon,
you must move the hands forwards by 12 hours.