how planning horizon influence the MRP running considering reservation with 202 movement type?

[alson2002]

Hello Experts,

I am confusing about reservation logic during MRP running of material planning.

I am trying to create reservation (transaction code MB21) with movement type 202 as below:

the requirements date for the component is within planning horizon as below(03.12.2021),currently my plant is assigned with planning horizon of 100 days :

afterwards run MRP to check planning result, and find the reservation updated to below sequence, as below screenshot reservation quantity is considered as calculation backward direction before the requirement date.

While I trying to create a reservation(same movement type 202) out of planning horizon(01.02.2022)

after MRP running, as below screenshot the result shows that reservation quantity is considered as calculation backward after the requirement date.

My question is why the calculation direction is different between within / out of planning horizon, and this behaviour is only working for 202 movement type reservation.

Could you please support on this question?

Thank you in advance!

[alson2002]

Dear team,

Could anyone support on this question?

Thank you!