CDO

This is my first time posting my question, I am sorry if there is a post-convention or style that I need to follow. In general, I just have some questions about the two operators that I mentioned in the title.

For the setreftime operator, is this the operator to do the calendar conversion? Or does it simply change the calendar information in the metadata?
As for the ensmean operator, can it recognize the difference in the calendar from input datasets? And what happens if I merge multiple datasets with different calendars, what is the output dataset calendar?

Background: I am trying to take the average of multiple datasets from different models (and datasets have different calendars), I am not sure if the ensmean is able to recognize the difference in the calendar when calculating the daily stat.

-Sam