Starting and ending days of activities

I don’t know exactly wich the starting day of my tasks is, so I would like to have my gantt project only with the duration of tasks indicated. Is it possible somehow not to display the exact calendar but only the number of days?

If you don’t know the exact date, choose any, e.g. Jan 1st.

Thanks for your answer. So there is no way to not show the calendar. I would not like to create misunderstandings about the project.

No, sorry. But maybe Jan 1st, 2100 will make it clear that date is not quite well defined…