Hi,
I can not see the screenshot. AT is an extended safety stock method. It needs the uncertainties in the supply chain are statistically independent from one another. AT is using alpha service level and reorder cycle methods. The alpha service level is event driven. Crucial here is the number of periods in which no shortfall quantities are expected. For example, if there is a service level of 90%, no shortfall quantities are expected in 90% of the periods. In the reorder cycle method, it is indicated that purchase orders can only be made for all t periods.
BR