https://docs.microsoft.com/en-us/dynamics365/customer-engagement/customize/create-and-edit-1n- relationships#relationship-behavior A parental table relationship is any 1:N table relationship where one of the cascading options in the Parental column of the following table is true.

Reference:
https://docs.microsoft.com/en-us/powerapps/maker/data-platform/create-edit-entity-relationships