Patek Philippe CALIBER 31-260 REG QA Manual Del Usuario página 17

date correction
To set the date, actuate the correction push piece
between 9 and 10 o'clock as many times as needed
to display the current date.
If you wish to set the date to the 30th or the 31st,
proceed as follows:
1. Make sure neither the 30th nor the 31st is indicated
(if necessary, set the date to the first day of
the month).
2. First, correct the month with the push piece at
10 o'clock (see below).
3. Then correct the date to the 30th or the 31st.
The mechanism that advances the month display is
already active on the 30th and the 31st. If you do
not follow the described procedure, the calendar
might be desynchronized, but the integrity of the
mechanism would not be affected.
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