How Rolling Forecast Target year is defined?

Hi,
We are trying to implement a rolling forecast.
When I changed the value of "Planning and Forecast Preparation" in the configure, the Year and Period fields in the "Enter Revenue - Rolling Forecast" form also changed, as shown in the image below.

However, when I open the form, there are no specific limitations on the Year and Period.

How are the Year and Period fields controlled in the forms?

And is it possible to apply the same controls to Plan1 cube?

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