If an impossible time is set to an RTC IC, what happens?

Real Time ClockHow to use

For example, June 31st is an impossible date. 25hr. 49min. is an impossible time. If such an impossible date or time is set to an RTC IC, the time or the date is written in the RTC_IC. Both time and date are carried according to the specified operation by the circuit of the RTC_IC.